A Physically Transient Form of Silicon Electronics
氧沉淀对p型硅的少子寿命的影响
JOURNAL OF APPLIED PHYSICS 110, 053713 (2011)
The effect of oxide precipitates on minority carrier lifetime in p-type silicon
J. D. Murphy,1,a) K. Bothe,2 M. Olmo,3 V. V. Voronkov,4 and R. J. Falster1,3
The formation of oxide precipitates is complicated by the morphological transformation they undergo as they grow.16,17 One study has focused on this transformation with
a)Author to whom correspondence should be addressed. Electronic mail: john.murphy@.
Inorganic fiber and process for the production the
专利名称：Inorganic fiber and process for theproduction thereof发明人：Takemi Yamamura,Toshihiro Ishikawa,Masaki Shibuya申请号：US07/870638申请日：19920420公开号：US05240888A公开日：19930831专利内容由知识产权出版社提供摘要：An inorganic fiber having excellent properties as a reinforcement for metals, plastics and rubbers, which has a surface layer portion and an inner layer portion, the surface layer portion having a composition continuously changing from the inner layer portion to the fiber surface, and which is composed of a basic constituent unit of;< P>(1) an amorphous substance composed of silicon, carbon, either titanium or zirconium, and oxygen,(2) an aggregate composed of;< P>crystalline fine particles formed of at least one selected from the group consisting of &bgr;-SiC, MC, a solid solution of &bgr;- SiC and MC, and MC.sub.1-x, and having a particle diameter of not more than 50 nm,amorphous SiO. sub.2, andMO. sub.2, or(3) a mixture of the above amorphous substance (1) with the above aggregate (2),< P>wherein M is titanium or zirconium and x is greater than 0 and less than 1,the inorganic fiber having an inner layer portion comprising 40 to 60% by weight of silicon, 20 to 40% by weight of carbon, 0.5 to 10% by weight of titanium or zirconium and 10 to 30% by weight of oxygen, and a surface layer portion comprising 0 to 40% by weight of silicon, 50 to 100% by weight of carbon, 0 to 8% by weight of titanium or zirconium and 0 to 25% by weight of oxygen.申请人：UBE INDUSTRIES, LTD.代理机构：Wenderoth, Lind & Ponack更多信息请下载全文后查看。
复旦大学王鹏飞半浮栅晶体管Science论文补充材料
/cgi/content/full/341/6146/640/DC1Supplementary Materials forA Semi-Floating Gate Transistor for Low-Voltage Ultrafast Memoryand Sensing OperationPeng-Fei Wang,* Xi Lin, Lei Liu, Qing-Qing Sun, Peng Zhou, Xiao-Yong Liu, Wei Liu, YiGong, David Wei Zhang*Corresponding author. E-mail: pfw@Published 9 August 2013, Science341, 640 (2013)DOI: 10.1126/science.1240961This PDF file includes:Materials and MethodsSupplementary TextFigs. S1 to S8ReferenceMaterials and MethodsThe Semi-Floating-Gate (SFG) transistors were fabricated using the 0.18-μm manufacturing technologies with specifically designed ion-implant processes and photolithography masks. The process flow and device structures are summarized in Fig. S1. First, a phosphorous-doped drain extension region was formed by ion-implantation and a 6-nm gate oxide layer was grown (Fig. S1A). Then a contact window inside the gate oxide was opened by lithography and buffered-HF wet etching. Boron was implanted into this contact window using the photo-resist as a masking layer (Fig. S1B). After that, the first boron-doped poly-Si layer was deposited and contacted the drain extension region via the aforementioned contact window. The Semi-FG pattern was then formed by lithography and reactive ion etching process which stops on the underlying thin SiO2 layer. This plasma-damaged SiO2 layer was then etched away and a 6 nm SiO2 dielectric was grown and nitrided as the inter-poly-dielectric. An n+-doped poly-Si was then deposited and the control-gate structure shown in Fig. S1C was formed. After the spacer processes, arsenic ions were implanted to form the heavily n-doped source and drain regions. The transmission electron microscope (TEM) cross-sections of the device are shown in Fig. S1D. In Fig. S1E, there is a SiO2 layer between the p+ doped poly-Si and the silicon substrate. However, at the position indicated in Fig. S1F, that SiO2 layer was etched away. With the p+ poly contacts the n-doped drain extension region, a floating pn-junction is formed and became the floating-gate of the device. The processed structures show very good process compatibility with the commercial dual-poly-gate manufacturing technology. Only minor modifications on the standard manufacturing process flow are required and high device yield on 8-inch silicon wafer is obtained. To further reduce the cell size, self-aligned techniques can be used to minimize the size of contact window between the p+ poly and the n-extension region.Supplementary TextThe DC characteristics of the SFG transistors were measured using a parameter analyzer (model Agilent B1500) and a RF probe-station. Figs. S2A to S2D compare the device symbols, the typical transfer I-V curves for MOSFET, FG-MOSFET, and two types of SFG transistors. For comparison, a MOSFET has a gate over the semiconductor channel (Fig. S2A) and a floating-gate MOSFET has a floating-gate between the control-gate and the semiconductor channel (Fig. S2B). The floating-gate MOSFET stores logic “0” with high V th or “1” with low V th by changing the amount of charge inside the floating-gate. By adding a diode or a gated diode between the floating-gate and the drain electrode of FG-MOSFET, a SFG transistor is realized. When the SFG transistor is exposed under light, the photo-carriers generated from the pn-junction diode will be partially collected by the floating-gate and in turn the I D-V CG curves will shift accordingly when changing the light intensity and exposure time. The change in threshold voltage of SFG transistor ( ) is expressed as , where is the change of the amount of charges inside the floating-gate (), is the floating-gate capacitance, and is the coupling ratio of control-gate (S1). During the light exposure process, is increased due to the photocurrent flowing into the floating-gate. The device symbol andthe measured transfer I D-V CG curves for SFG transistor for light sensing are shown in Fig. S2C. It can be seen that V th decreases when the light intensity increases. The device symbol and the measured I D-V CG curves of a SFG transistor optimized for memory function are shown in Fig. S2D. Compared to the SFG transistor shown in Fig. S2C, this SFG cell extends the control-gate over the pn-diode. A gate controlled diode or Tunneling FET (TFET) is formed and connects the semi-floating-gate to the drain. As a result, the TFET can now be used to charge or discharge the floating-gate. The current of TFET depends on the band-to-band tunneling generation rate, i.e. . G BTBT is the band-to-band tunneling generation rate, and it is expressed as. A BTBT and B BTBT are constants, E g is the band-gap energy, and E is the magnitude of the electric field. With a higher V D, the electric field increases and the charge current increases exponentially. As shown in Fig. S2D, the threshold voltage decreases when the drain voltage increases. Fast switching behavior is also observed in the transfer I D-V CG curves. The subthreshold swing even reaches 30 mV/dec when V D equals 3.0V.Because SFG transistor has an entirely new device structure, process and device simulations were carried out using Silvaco TCAD tools before device fabrication. First, the process simulations were performed. The resulted structure was then imported to the device simulator for transient behavior simulation. The ion-implantation conditions were designed for the optimized device performance from the device simulation. Asymmetric doping profiles for the source and drain of the embedded P-TFET are specifically designed to obtain the favorable device electrical behavior. Since the processing parameters were obtained from the process simulation results, the simulated structure is almost identical to the experimental device structure shown in Fig. S1D. The models for simulating a conventional MOSFET were included in the SFG transistor simulation. In addition, Kane’s local band-to-band tunneling model was included for simulating the tunneling current during the device operation. Fig. S3A - S3D display the simulated device structures with current and potential contours. The writing-1 operation is with V CG = -2.0 V and V D = 2.0 V. During the writing-1 operation, the drain is positively biased and the semi-floating-gate has a negative potential, resulting in current flows from the drain to the semi-floating-gate (Fig. S3A). The writing-0 operation is with V CG = 2.0 V and V D = 0 V. During the writing-0 operation, the n+ drain is biased with 0 V and the semi-floating-gate potential is elevated by the capacitive coupling of increased V CG, resulting in current flows from the semi-floating-gate to the drain (Fig. S3B). After writing-1 and writing-0 operations, the potential contours for the “1” and “0” devices at the standby status are plotted in Fig. S3C and S3D. It can be seen that the semi-floating-gate potential of the “1” state is 0.75 V, which is 1.64 V higher than that of the “0” state with the same bias conditions.The transient electrical behavior of the simulated device is shown in Fig. S3E. With the band-to-band tunneling model turned on, the high-speed memory function is realized (black line in the read-out current subfigure of Fig. S3E). It is found from the simulation that the gate-controlled band-to-band tunneling current is the key to high speed writingoperation, especially at the nano-second level. The green line in the read-out current subfigure of Fig. S3E is simulated with the band-to-band tunneling model turned off. It can be seen that writing-1 operation does not work with the same voltage setting. For comparison, the measured transient operation characteristic of the SFG transistor is shown in Fig. S3F. The transient behavior of the measured device is similar to the simulated device with band-to-band tunneling model.The transient behaviors of SFG transistors were measured using the circuit configuration shown in Fig. S4A. The measurement environment includes a RF probe-station, a pulse generator, a transimpedance amplifier circuit, and a high-speed oscilloscope. Two channel signal pulses were generated by the pulse generator (Agilent 81160A) and coupled to the drain and the control-gate electrodes of SFG transistor. A transimpedance amplifier circuit (Fig. S4B) was designed to convert the read-out current of SFG transistor to voltage signal for oscilloscope tracing. In Fig. S4C, the examples of traces captured by the oscilloscope during transient operation are shown. The writing-1 operation was performed by pulses of V D = 2V and V CG = -2V for 3 ns. Then, during the read operation, the voltage drop on the feedback resistor R f was measured by the oscilloscope and then converted to the I drain signal shown in Fig. S4D. It can be seen the readout current is about 2 μA after a 3-ns writing “1” operation. Unlike the conventional DRAM cell, the read operation of the SFG memory device is non-destructive because of its gain cell nature, which means no write-back operation is needed after the reading operation.In order to evaluate the operation speed of SFG transistor for memory application, short writing time with the target pulse width of 0.6 ns was executed (Fig. S5A). Due to the parasitic capacitance of the measurement cables, the rising / falling edges were 0.9 ns and the actual peak width at half height (PWHH) was increased to 1.3 ns. However, the writing-1 and writing-0 operations were successfully demonstrated in Fig. S5B. Meanwhile, it was found that the off-chip read-out circuit oscillates at the beginning of reading operation. Figs. S5B to S5D show the transient operation of the devices with different reading operation time. The reading operation duration was 9 μs in Fig. S5B. First, a writing-1 operation was performed with V D= 2V and V CG= -1.8V. A read-out current of about 1.5 μA was measured for the “1” cell. Then, a writing-0 operation was performed with V D= 0V and V CG= 2V. A very small current representing “0” was measured for the “0” cell. It can be seen that the read-out current oscillates at the beginning of the reading operation. With longer reading time such as 22.4 μs and 45 μs shown in Figs. S5C and S5D, the read-out current became stable. The oscillation was caused by the amplification circuit board (Fig. S4B) which can be improved by using the on-chip read-out circuits. Meanwhile, higher operation speed is expected by reducing the rising / falling edges of the pulses when using the integrated supporting circuits.In Figure S6A, 40 test devices were tested. The operation sequence was writing-0, reading, writing-1, and then reading. A “0” could be written into the transistor with V D of -1V and V CG of 2 V for 3 ms. During the subsequent reading operation, a very small drain current of 30 nA was measured with V D = 2 V and V CG = 2 V. After a writing-1 operation at V D =2 V and V CG = -2 V for 3 ms, the threshold voltage was lowered and a large draincur rent of about 2 μA was measured with V D = 2 V and V CG = 2 V. The wafer map of the reading-1 drain current of 40 test devices showed high uniformity across the whole wafer. The retention time and operation endurance properties were evaluated. In Fig. S6B, the retention time for “0” cell reaches 1 second at room temperature, while the “1” cell does not have retention issue because the semi-floating-gate voltage will be pinned to the drain voltage in the standby state. The retention performance of “0” is good because of the low leakage current of reversely biased p-n structure in the standby status. In Fig. S6C, the device operation endurance was investigated by repeating the full operation sequences. Almost no degradation was observed for 1012cycles of operation. The extrapolated endurance reaches 1015, which is far beyond the endurance of 106 for the conventional floating-gate memory cell.As a memory device, the immunity to various disturb mechanisms is also very important. Figs. S7A to S7F show the disturb properties of SFG memory cell measured at room temperature. Six types of disturb mechanisms on “1” and “0” cells are characterized. Most of the disturb endurances exceed 100 ms except for the disturbance of the writing-0 control-gate voltage on the “1” cell when V D at standby status is set to 1.0 V. During this writing-0 V CG disturb with V CG = 2.0 V and V D = 1.0 V, the pn junction will be weakly forward-biased if “1” is already stored inside the cell. The disturb endurances can be further improved by optimizing the operation voltages and the operation sequences. Using the image sensing SFG transistor, an imaging array can be configured. In Fig. S8, the schematic view of the SFG image sensor array is shown. The source lines and bit lines are arranged above the shallow trench isolation (STI) structure to maximize the fill factor. Using SFG cell as an APS cell, the pixel density of image sensing chip can be increased and the reading operation becomes non-destructive.Fig. S1.Brief summary of the process flow for fabricating the SFG transistor (A to C) and the TEM pictures of SFG transistor along the channel direction (D to F). Inset E is taken from the MOSFET channel where poly-Si on SiO2 can be seen. Inset F is taken from the contact interface between semi-floating-gate and n-doped drain extension region whereno oxide interface exists.Fig. S2Device symbols and transfer characteristics for MOSFET (A), FG-MOSFET (B), and SFG transistors (C, D). The semi-floating-gate is realized by connecting the floating-gate of FG-MOSFET to the drain via a pn junction diode. When the diode works as a photo-diode, photo-sensing function can be realized. When extending the control-gate over the diode, an embedded TFET is formed and dramatically accelerates the writing-1operation.Fig. S3(A, B) Simulated current contours of writing-1 operation and writing-0 operation. During the writing-1 operation, the drain is positively biased and the semi-floating-gate has a negative potential. Current will flow from the drain to the semi-floating-gate. During the writing-0 operation, the n+ drain is biased with 0 V and the semi-floating-gate potential is elevated by the capacitive coupling of increased V CG. Current will flow from the semi-floating-gate to the drain. (C, D) Simulated potential contours for the “1” and “0” devices at the standby state. The semi-floating-gate potential of the “1” state is higher than that of the “0” state with the same external voltages. (E) Simulated transient operation of the SFG transistor. V CG, V D, and the read out I D are displayed separately. In the read out I D figure the simulation results with or without the band-to-band tunneling model are compared. Device does not work when the band-to-band tunneling model is turned off in the simulation. (F) Experimental transient operations are shown for comparison with thesimulation results of Fig. S3E.Fig. S4(A) Transient measurement circuit. The measurement environment includes a RF probe-station, a pulse generator, a transimpedance amplifier circuit, and a high-speed oscilloscope. (B) Specific transimpedance amplifier circuit for converting the current signal to voltage signal for oscilloscope tracing. (C) Examples of measured voltage signals shown on the screen of oscilloscope. (D) Control-gate voltage, drain voltage, and the read-out current of a SFG transistor using 3-ns writing-1 pulse. The voltages are measured directly and the read-out current is converted from the voltage-drop on thefeedback resistor.Fig. S5(A) Measured drain voltage and control-gate voltage pulses for writing “1” and writing “0”, where the peak-width-at-half-height (PWHH) is measured as 1.3 ns. Transient measurement sequence of writing “1” - standby - reading - writing “0” - standby -reading with various reading pulse widths of 9 μs (B), 22.5 μs (C), and 45μs (D).Fig. S6(A) Measured reading-1 drain current wafer map and two transient operation cycles of 40 SFG transistors. The operation sequence is writing-0, reading, writing-1, and then reading. (B) Data retention time of “1” and “0” at room temperature. The read-out operation is performed with various standby periods after the writing operation. (C) Measured operation endurance property. Full writing-reading sequences are repeated with3 ns writing time.Fig. S7Disturb performances of SFG memory cell measured at room temperature. (A) Writing-1 V D disturb on the “1” and “0” cells. (B) Writing-1 V CG disturb on the “1” and “0” cells.(C) Writing-0 V D disturb on the “1” and “0” cells. (D) Writing-0 V CG disturb on the “1” and “0” cells. (E) Reading-operation V D disturb on the “1” and “0” cells. (F) Reading-operation V CG disturb on the “1” and “0” cells.Fig. S8Schematic view of the SFG image sensor array. The source lines and bit lines arearranged above the shallow trench isolation (STI) structure to maximize the fill factor.ReferencesS1. P. Pavan, L. Larcher, and A. Marmiroli, Floating gate devices: operation and compact modeling (Kluwer Acdemic Publisher, Dordrecht, 2004), pp. 37-40.。
碳化硅功率器件的发展与数值建模
科技创新与应用Technology Innovation and Application研究视界2021年13期碳化硅功率器件的发展与数值建模李国鑫（上海电力大学，上海200090）1碳化硅材料的发展随着集成电路与微电子的发展，传统的半导体材料由于自身的结构和局限性，在高导热、高电场的工作环境下已难堪大任，碳化硅材料以其卓越的物理特性引起了人们的关注，并成为了继第一代元素半导体硅和第二代化合物半导体磷化镓等之后发展迅速的第三代半导体材料[1-2]。
碳化硅电子器件的发展已有多年，在1907年首次观察到碳化硅的电致发光现象，且于1923年利用碳化硅制成了第一种LED 。
但早期大多数关于碳化硅的研究是通过升华法生产的，目前最常用的方法是物理气相输运法（Physical VaporTransport ，PVT ）。
表1比较了碳化硅材料和硅材料的基本物理特性。
不难得出，与普通的硅材料相比，碳化硅材料具有更加优良的物理特性。
包括其更加宽泛的禁带、更高的击穿场强、热导率及击穿场强[3-4]。
因此，深入研究碳化硅结构并解决其高界面态是推动碳化硅功率器件发展的必经之路。
24H-SiC MOSFET 器件结构半导体功率器件一般可分为两种，即MOS 器件与双极结型器件。
图1中展示了一种基本的碳化硅MOS 器件的结构，该结构具有工频高，栅压可控的优点。
然而，在SiO 2/SiC存在的高界面态却阻碍了碳化硅MOS 在航天航空及通信等领域的广泛应用。
摘要：近年来，碳化硅、氮化镓等宽禁带半导体材料的发展引起了人们的广泛关注。
凭借其高导热性、高击穿电场和可生长天然氧化物的能力，在航天航空及通信等领域得到了广泛应用。
然而，碳化硅功率器件在开发中也有一定的局限性，碳化硅功率器件的高界面态成为制约器件性能的主要因素。
因此，碳化硅器件还需要更加深入地了解与应用。
文章比较了第三代半导体材料碳化硅与第一代元素半导体硅材料的物理特性，并提出了研究碳化硅材料数值分析所需的模型，为今后碳化硅功率器件的研究打下基础。
半导体简介PPT课件
A major difference between semiconductors and conductors is their electrical behavior at different temperatures. In general, when you heat up a semiconductor it’s resistance to the flow of electricity decreases (or its conductance increases). In metals the opposite happens. As the temperature of a metal increases then its resistance also increases (or conductance decreases).
All of these elements can exist in multiple physical forms. Carbon can take many forms such as graphite (a form a bit like a classical metal) which conducts electricity very well or diamond (a crystalline form) which is an insulator.
• Some compounds of elements of Group VI with elements of Group II.
6
Probably the most versatile elements are those with four electrons in their outer shell (Group IV: carbon, silicon, germanium, tin, lead). Because of the fact that they can have four bonds to four other elements, covalent compounds of endless complexity can be formed. (Indeed DNA is a single carbon-based molecule.)
半导体专业名词解释
Cd cadmium
AWS advanced wet station
Manufacturing and Science
Sb antimony
===B===
B billion; boron
Ba barium
BARC bottom antireflective coating
BASE Boston Area Semiconductor Education (Council)
ACF anisotropic conductive film
ACI after-clean inspection
ACP anisotropic conductive paste
ACT alternative control techniques; actual cycle time
Al aluminum
ALD atomic layer deposition
ALE atomic layer epitaxy; application logic element
ALS advanced light source; advanced low-power Schottky
===A===
A/D analog to digital
AA atomic absorption
AAS atomic absorption spectroscopy
ABC activity-based costing
ABM activity-based management
AC alternating current; activated carbon
激光加热下不同形貌硅片的热力学性能分析
- 44 —
装 备 机 械 2021 No.2
Calculation • Analyses
系 统 的 可 靠 运 行 [6_7]。硅 片 在 磨 削 加 工 时 会 造 成 表 面 磨 损 ，强 度 因 此 受 到 影 响 。对 集 成 电 路 和 硅 器 件 进 行 研 究 发 现 ，硅 片 在 高 温 工 艺 下 出 现 弯 曲 、翘曲也 是常 见 的 现 象 ~°]。如何提高硅片的机械强度和热 应 力 ，是一个重要课题。
的 ，没有光线穿透硅片。由此，激光产生的所有热量
都作用在硅片表面。
热量0 为：
Q = 〇j A { T ^ - T 2 ) / e
(6)
式 中 为 硅 片 温 度 ; r2 为周围环境温度;《为导热
系 数 ,出 为 5.67><1〇-8评/ ( 1112 .1〇 ^ 为辐射率，与
娃片表面性能有关，数 值 介 于 0 和 1 间 ' 取 0. 8;4
对 模 型 输 入 材 料 ，采 用 四 面 体 网 格 对 模 型 进 行 网格化设置，在硅片上表面施加同等压力，在硅片下 表 面 四 周 施 加 固 定 约 束 ，分 析 不 同 表 面 形 貌 硅 片 的 应 力 、应 变 ，得 到 应 变 云 图 如 图 3 所示 ，应力云图如 图 4 所示。
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半导体物理与器件英语
半导体物理与器件英语Semiconductor Physics and DevicesThe field of semiconductor physics and devices is a crucial aspect of modern technology, as it underpins the development of a wide range of electronic devices and systems that have transformed our daily lives. Semiconductors, which are materials with electrical properties that lie between those of conductors and insulators, have been the backbone of the digital revolution, enabling the creation of integrated circuits, transistors, and other essential components found in smartphones, computers, and a myriad of other electronic devices.At the heart of semiconductor physics is the study of the behavior of electrons and holes within these materials. Electrons, which are negatively charged particles, and holes, which are the absence of electrons and carry a positive charge, are the fundamental charge carriers in semiconductors. The interactions and movement of these charge carriers within the semiconductor lattice structure are governed by the principles of quantum mechanics and solid-state physics.One of the fundamental concepts in semiconductor physics is theenergy band structure. Semiconductors have a unique energy band structure, with a filled valence band and an empty conduction band separated by an energy gap. The size of this energy gap determines the semiconductor's electrical properties, with materials having a smaller energy gap being more conductive than those with a larger gap.The ability to manipulate the energy band structure and the behavior of charge carriers in semiconductors has led to the development of a wide range of electronic devices. The most prominent of these is the transistor, a fundamental building block of modern electronics. Transistors are used to amplify or switch electronic signals and power, and they are the essential components in integrated circuits, which are the heart of digital devices such as computers, smartphones, and various other electronic systems.Another important class of semiconductor devices are diodes, which are two-terminal devices that allow the flow of current in only one direction. Diodes are used in a variety of applications, including power supplies, rectifiers, and light-emitting diodes (LEDs). LEDs, in particular, have become ubiquitous in modern lighting and display technologies, offering improved energy efficiency, longer lifespan, and enhanced color quality compared to traditional incandescent and fluorescent light sources.Semiconductor devices are not limited to electronic applications; they also play a crucial role in optoelectronics, a field that deals with the interaction between light and electronic devices. Photodetectors, such as photodiodes and phototransistors, are semiconductor devices that convert light into electrical signals, enabling a wide range of applications, including imaging, optical communication, and solar energy conversion.The development of semiconductor physics and devices has been a continuous process, driven by the relentless pursuit of improved performance, efficiency, and functionality. Over the past several decades, we have witnessed remarkable advancements in semiconductor technology, with the miniaturization of devices, the introduction of new materials, and the development of innovative device architectures.One of the most significant trends in semiconductor technology has been the scaling of transistor dimensions, often referred to as Moore's Law. This observation, made by Intel co-founder Gordon Moore in 1965, predicted that the number of transistors on a microchip would double approximately every two years, leading to a dramatic increase in computing power and a corresponding decrease in device size and cost.This scaling has been achieved through a combination ofadvancements in fabrication techniques, material engineering, and device design. For example, the use of high-k dielectric materials and the implementation of FinFET transistor architectures have allowed for continued scaling of transistor dimensions while maintaining or improving device performance and power efficiency.Beyond the scaling of individual devices, the integration of multiple semiconductor components on a single integrated circuit has led to the development of increasingly complex and capable electronic systems. System-on-a-chip (SoC) designs, which incorporate various functional blocks such as processors, memory, and input/output interfaces on a single semiconductor die, have become ubiquitous in modern electronic devices, enabling greater functionality, reduced power consumption, and improved overall system performance.The future of semiconductor physics and devices holds immense promise, with researchers and engineers exploring new materials, device architectures, and application domains. The emergence of wide-bandgap semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), has opened up new possibilities in high-power, high-frequency, and high-temperature electronics, enabling advancements in areas like electric vehicles, renewable energy systems, and communication networks.Additionally, the integration of semiconductor devices with otheremerging technologies, such as quantum computing, neuromorphic computing, and flexible/wearable electronics, is paving the way for even more transformative applications. These developments have the potential to revolutionize fields ranging from healthcare and transportation to energy and communication, ultimately enhancing our quality of life and shaping the technological landscape of the future.In conclusion, the field of semiconductor physics and devices is a cornerstone of modern technology, underpinning the development of a vast array of electronic devices and systems that have become indispensable in our daily lives. The continuous advancements in this field, driven by the relentless pursuit of improved performance, efficiency, and functionality, have been instrumental in driving the digital revolution and shaping the technological landscape of the21st century. As we move forward, the future of semiconductor physics and devices promises even more remarkable innovations and transformative applications that will continue to shape our world.。
硅外延厚度稳定性控制
0 引言 由于外延工艺可以精确控制器件掺杂浓度，且
得到的外延层中不含氧和碳，因此越来越成为关注 的焦点。采用外延层可以提供器件所需要的电阻率 及无缺陷的表面使得器件性能得以优化，因而广泛 用于双极型晶体管器件、分立器件、瞬态电压抑制 器及超结器件。集成电路制造业一般采用化学气相 沉积的方法生长外延层，通过采用不同的掺杂气体 如砷烷（AsH3），硼烷（B2H6）或磷烷（PH3）得 到需要的电阻率。目前用于外延的硅源气体主要有 四种：四氯化硅(SiCl4)、三氯氢硅（Trichlorosilane TCS)、二氯二氢硅(Dichlorosilane DCS)和硅烷 （SiH4），因为DCS工艺温度比较低且缺陷密度 低，更适合生长高质量的薄外延层，因此减压工艺 通常采用二氯二氢硅作为主要的硅源气体，常压工
图6 DCS蒸汽压与温度关系曲线 （1）我们车间平时的温度是控制在22℃正负 0.5℃，虽然从钢瓶到gas panel加热带设定温度是 35℃，但gas panel 处并没有安装加热带，而且gas panel里有排风，温度等于或低于车间温度，在21℃ 附近冷凝的压力10psi以下, 当DCS管路里气体压力接 近液化的临界点时很容易发生液化，我们确实观察 到VMB处显示屏上的气体压力显示是10psi，恰好在 液化的临界点。 （2）当机台闲置时，DCS停止流动，静态压力 比流动时压力要高出1～2psi，更容易引起冷凝。 （3）每次岁修时，DCS管路会被抽空，复机时 重新流气，钢瓶压力会被重新调整，一旦钢瓶出口 压力过高，很容易达到DCS的液化点造成冷凝，据 此解释了为什么每次都是在岁修之后发生流量不稳 的现象。另外我们发现从同一钢瓶出来的气体经三 个VMB分配不同设备，同一个VMB上又接了10个外 延腔，不同的外延腔DCS flow会有所不同因而压力 会波动，造成气体流量不稳。 综合以上分析，针对DCS流量不稳的问题，我
科技英语翻译1
► 2）通顺易懂 ► 译文的语言符合译语语法结构及表达习惯，容易为读者所理解和接受。
► A. When a person sees, smells, hears or touches something, then he is perceiving.
2. Cramped(狭窄的) conditions means that passengers’ legs cannot move around freely.
空间狭窄，旅客的两腿就不能自由活动。
3. All bodies are known to possess weight and occupy space.
忠实、通顺（普遍观点）
► 科技英语文章特点：(well-knit structure;tight logic;various styles)结构严谨，逻辑严密，文体多样
1. 科技翻译的标准：准确规范，通顺易懂，简洁明晰 1）准确规范
所谓准确，就是忠实地，不折不扣地传达原文的全部信息内容。 所谓规范，就是译文要符合所涉及的科学技或某个专业领域的专业语言表
实验结果等，而不是介绍这是这些结果，理论或现象是由谁发 明或发现的。
► In this section, a process description and a simplified process flowsheet are given for each DR process to illustrate the types of equipment used and to describe the flow of materials through the plant. The discussion does not mention all the variations of the flowsheet which may exist or the current status of particular plants. In the majority of the DR processes described in this section, natural gas is reformed in a catalyst bed with steam or gaseous reduction products from the reduction reactor. Partial oxidation processes which gasify liquid hydrocarbons, heavy residuals and coal are also discussed. The reformer and partial oxidation gasifier are interchangeable for several of the DR processes.
广工电材微电子专业英语翻译译文(考试重点)
Semiconductor Materials• 1.1 Energy Bands and Carrier Concentration• 1.1.1 Semiconductor Materials• Solid-state materials can be grouped into three classes—insulators(绝缘体）, semiconductors, and conductors. Figure 1-1shows the electrical conductivities δ (and the correspondingresistivities ρ≡1/δ)associated with(相关）some important materialsin each of three classes. Insulators such as fused（熔融） quartz and glass have very low conductivities, in the order of 1E-18 to 1E-8S/cm;固态材料可分为三种：绝缘体、半导体和导体。
图1－1 给出了在三种材料中一些重要材料相关的电阻值（相应电导率ρ≡1/δ)。
绝缘体如熔融石英和玻璃具有很低电导率，在10-18 到10-8 S/cm;and conductors such as aluminum and silver have high conductivities, typically from 104 to 106 S/cm. Semiconductors have conductivities between those of insulators and those of conductors. The conductivity of a semiconductor is generally sensitive to temperature, illumination（照射）, magnetic field, and minute amount of impurity atoms. This sensitivity in conductivity makes the semiconductor one of the most important materials for electronic applications.导体如铝和银有高的电导率，典型值从104到106S/cm;而半导体具有的电导率介乎于两者之间。
电力电子专业英语单词汇总
电力电子专业英语单词汇总电路的基本概念及定律电源 source电压源 voltage source电流源 current source理想电压源 ideal voltage source理想电流源 ideal current source伏安特性 volt-ampere characteristic电动势 electromotive force电压 voltage电流 current电位 potential电位差 potential difference欧姆 Ohm伏特 Volt安培 Ampere瓦特 Watt焦耳 Joule电路 circuit电路元件 circuit element电阻 resistance电阻器 resistor电感 inductance电感器 inductor电容 capacitance电容器 capacitor电路模型 circuit model参考方向 reference direction参考电位 reference potential欧姆定律Ohm’s law基尔霍夫定律Kirchhoff’s law基尔霍夫电压定律Kirchhoff’s voltage law（KVL）基尔霍夫电流定律Kirchhoff’s current law（KCL）结点 node支路 branch回路 loop网孔 mesh支路电流法 branch current analysis网孔电流法 mesh current analysis结点电位法 node voltage analysis电源变换 source transformations叠加原理 superposition theorem网络 network无源二端网络 passive two-terminal network有源二端网络 active two-terminal network戴维宁定理Thevenin’s theorem诺顿定理Norton’s theorem开路（断路）open circuit 短路 short circuit开路电压 open-circuit voltage短路电流 short-circuit current交流电路直流电路 direct current circuit (dc)交流电路 alternating current circuit (ac)正弦交流电路 sinusoidal a-c circuit平均值 average value有效值 effective value均方根值root-mean-squire value (rms)瞬时值 instantaneous value电抗 reactance感抗 inductive reactance容抗 capacitive reactance法拉 Farad亨利 Henry阻抗 impedance复数阻抗 complex impedance相位 phase初相位 initial phase相位差 phase difference相位领先 phase lead相位落后 phase lag倒相，反相 phase inversion频率 frequency角频率 angular frequency赫兹 Hertz相量 phasor相量图 phasor diagram有功功率 active power无功功率 reactive power视在功率 apparent power功率因数 power factor功率因数补偿 power-factor compensation串联谐振 series resonance并联谐振 parallel resonance谐振频率 resonance frequency频率特性 frequency characteristic幅频特性amplitude-frequency response characteristic相频特性 phase-frequency response characteristic 截止频率 cutoff frequency品质因数 quality factor通频带 pass-band带宽 bandwidth (BW)滤波器 filter一阶滤波器 first-order filter二阶滤波器 second-order filter低通滤波器 low-pass filter高通滤波器 high-pass filter带通滤波器 band-pass filter带阻滤波器 band-stop filter转移函数 transfer function波特图 Bode diagram傅立叶级数 Fourier series三相电路 three-phase circuit三相电源 three-phase source对称三相电源 symmetrical three-phase source对称三相负载 symmetrical three-phase load相电压 phase voltage相电流 phase current线电压 line voltage线电流 line current三相三线制 three-phase three-wire system三相四线制 three-phase four-wire system三相功率 three-phase power星形连接 star connection(Y-connection)三角形连接triangular connection(D- connection ,delta connection)中线 neutral line电路的暂态过程分析暂态 transient state稳态 steady state暂态过程，暂态响应 transient response换路定理 low of switch一阶电路 first-order circuit三要素法 three-factor method时间常数 time constant积分电路 integrating circuit微分电路 differentiating circuit磁路与变压器磁场magnetic field磁通 flux磁路 magnetic circuit磁感应强度 flux density磁通势 magnetomotive force磁阻 reluctance电动机直流电动机 dc motor交流电动机 ac motor异步电动机 asynchronous motor同步电动机 synchronous motor三相异步电动机 three-phase asynchronous motor 单相异步电动机 single-phase asynchronous motor 旋转磁场 rotating magnetic field定子 stator转子 rotor转差率 slip起动电流 starting current起动转矩 starting torque 额定电压 rated voltage额定电流 rated current额定功率 rated power机械特性 mechanical characteristic继电器-接触器操纵按钮 button熔断器 fuse开关 switch行程开关 travel switch继电器 relay接触器 contactor常开(动合)触点 normally open contact常闭(动断)触点 normally closed contact时间继电器 time relay热继电器 thermal overload relay中间继电器 intermediate relay可编程操纵器（PLC）可编程操纵器 programmable logic controller语句表 statement list梯形图 ladder diagram半导体器件本征半导体intrinsic semiconductor掺杂半导体doped semiconductorP型半导体 P-type semiconductorN型半导体 N--type semiconductor自由电子 free electron空穴 hole载流子 carriersPN结 PN junction扩散 diffusion漂移 drift二极管 diode硅二极管 silicon diode锗二极管 germanium diode阳极 anode阴极 cathode发光二极管 light-emitting diode (LED)光电二极管 photodiode稳压二极管 Zener diode晶体管（三极管） transistorPNP型晶体管 PNP transistorNPN型晶体管 NPN transistor发射极 emitter集电极 collector基极 base电流放大系数 current amplification coefficient 场效应管 field-effect transistor (FET)P沟道 p-channelN沟道 n-channel结型场效应管 junction FET（JFET）金属氧化物半导体 metal-oxide semiconductor (MOS)耗尽型MOS场效应管depletion mode MOSFET （D-MOSFET）增强型MOS场效应管enhancement mode MOSFET （E-MOSFET）源极 source栅极 grid漏极 drain跨导 transconductance夹断电压 pinch-off voltage热敏电阻 thermistor开路 open短路 shorted基本放大器放大器 amplifier正向偏置 forward bias反向偏置 backward bias静态工作点 quiescent point (Q-point)等效电路 equivalent circuit电压放大倍数 voltage gain总的电压放大倍数 overall voltage gain饱与 saturation截止 cut-off放大区 amplifier region饱与区 saturation region截止区 cut-off region失真 distortion饱与失真 saturation distortion截止失真 cut-off distortion零点漂移 zero drift正反馈 positive feedback负反馈 negative feedback串联负反馈 series negative feedback并联负反馈 parallel negative feedback共射极放大器 common-emitter amplifier射极跟随器 emitter-follower共源极放大器 common-source amplifier共漏极放大器 common-drain amplifier多级放大器 multistage amplifier阻容耦合放大器resistance-capacitance coupled amplifier直接耦合放大器 direct- coupled amplifier输入电阻 input resistance输出电阻 output resistance负载电阻 load resistance动态电阻 dynamic resistance负载电流 load current旁路电容 bypass capacitor耦合电容 coupled capacitor直流通路 direct current path交流通路 alternating current path 直流分量 direct current component交流分量 alternating current component变阻器（电位器）rheostat电阻（器）resistor电阻（值）resistance电容（器）capacitor电容（量）capacitance电感（器，线圈）inductor电感（量），感应系数inductance正弦电压 sinusoidal voltage集成运算放大器及应用差动放大器 differential amplifier运算放大器 operational amplifier(op-amp)失调电压 offset voltage失调电流 offset current共模信号 common-mode signal差模信号 different-mode signal共模抑制比 common-mode rejection ratio (CMRR) 积分电路 integrator（circuit）微分电路 differentiator（circuit）有源滤波器 active filter低通滤波器 low-pass filter高通滤波器 high-pass filter带通滤波器 band-pass filter带阻滤波器 band-stop filter波特沃斯滤波器 Butterworth filter切比雪夫滤波器 Chebyshev filter贝塞尔滤波器 Bessel filter截止频率 cut-off frequency上限截止频率 upper cut-off frequency下限截止频率 lower cut-off frequency中心频率 center frequency带宽 Bandwidth开环增益 open-loop gain闭环增益 closed-loop gain共模增益 common-mode gain输入阻抗 input impedance电压跟随器 voltage-follower电压源 voltage source电流源 current source单位增益带宽unity-gain bandwidth频率响应 frequency response频响特性（曲线）response characteristic波特图 the Bode plot稳固性stability补偿 compensation比较器 comparator迟滞比较器 hysteresis comparator阶跃输入电压step input voltage仪表放大器 instrumentation amplifier隔离放大器 isolation amplifier对数放大器 log amplifier反对数放大器antilog amplifier反馈通道 feedback path反向漏电流 reverse leakage current相位phase相移 phase shift锁相环 phase-locked loop(PLL)锁相环相位监测器 PLL phase detector与频 sum frequency差频 difference frequency波形发生电路振荡器 oscillatorRC振荡器 RC oscillatorLC振荡器 LC oscillator正弦波振荡器 sinusoidal oscillator三角波发生器 triangular wave generator方波发生器square wave generator幅度 magnitude电平level饱与输出电平（电压） saturated output level功率放大器 power amplifier交越失真 cross-over distortion甲类功率放大器 class A power amplifier乙类推挽功率放大器class B push-pull power amplifierOTL功率放大器output transformerless power amplifierOCL功率放大器output capacitorless power amplifier直流稳压电源半波整流 full-wave rectifier全波整流 half-wave rectifier电感滤波器 inductor filter电容滤波器 capacitor filter串联型稳压电源 series (voltage) regulator开关型稳压电源 switching (voltage) regulator集成稳压器 IC (voltage) regulator晶闸管及可控整流电路晶闸管 thyristor单结晶体管 unijunction transistor（UJT）可控整流 controlled rectifier可控硅 silicon-controlled rectifier峰点 peak point谷点 valley point操纵角 controlling angle导通角 turn-on angle门电路与逻辑代数二进制 binary二进制数 binary number十进制 decimal十六进制 hexadecimal 二-十进制 binary coded decimal （BCD）门电路 gate三态门tri-state gate与门 AND gate或者门 OR gate非门 NOT gate与非门 NAND gate或者非门 NOR gate异或者门 exclusive-OR gate反相器 inverter布尔代数 Boolean algebra真值表 truth table卡诺图 the Karnaugh map逻辑函数 logic function逻辑表达式 logic expression组合逻辑电路 combination logic circuit译码器 decoder编码器 coder比较器 comparator半加器 half-adder全加器 full-adder七段显示器 seven-segment display时序逻辑电路 sequential logic circuitR-S 触发器 R-S flip-flopD触发器 D flip-flopJ-K触发器 J-K flip-flop主从型触发器 master-slave flip-flop置位 set复位 reset直接置位端direct-set terminal直接复位端direct-reset terminal寄存器 register移位寄存器 shift register双向移位寄存器bidirectional shift register 计数器 counter同步计数器 synchronous counter异步计数器asynchronous counter加法计数器 adding counter减法计数器 subtracting counter定时器 timer清除（清0）clear载入 load时钟脉冲 clock pulse触发脉冲 trigger pulse上升沿 positive edge下降沿 negative edge时序图 timing diagram波形图 waveform单稳态触发器 monostable flip-flop双稳态触发器 bistable flip-flop无稳态振荡器 astable oscillator晶体 crystal 555定时器 555 timer模拟信号 analog signal数字信号 digital signalAD转换器analog -digital converter (ADC)DA转换器 digital-analog converter (DAC)半导体存储器只读存储器 read-only memory（ROM）随机存取存储器 random-access memory（RAM）可编程ROM programmable ROM（PROM）常见英文缩写解释（按字母顺序排列）：ASIC: Application Specific Integrated Circuit. 专用ICCPLD: Complex Programmable Logic Device. 复杂可编程逻辑器件EDA: Electronic Design Automation. 电子设计自动化FPGA: Field Programmable Gate Array. 现场可编程门阵列GAL: Generic Array Logic. 通用阵列逻辑HDL: Hardware Description Language. 硬件描述语言IP: Intelligent Property. 智能模块PAL: Programmable Array Logic. 可编程阵列逻辑RTL: Register Transfer Level. 寄存器传输级描述）SOC: System On a Chip. 片上系统SLIC: System Level IC. 系统级ICVHDL: Very high speed integrated circuit Hardware Description Language. 超高速集成电路硬件描述语言。
新视野大学英语第三版第四册英语读写答案
新视野大学英语第三版第四册英语读写答案Unit1Text AText A：Language focus：Words in usecrumbleddiscernsurpassshrewdconversiondistortradiantingeniousstumpedpropositionText A：Language focus：delicacybankruptcyaccountancysecrecyvacancyurgencyatmosphericmagnetmetallicgloomguiltmasteryText A：Language focus：bankruptciesatmosphericdelicaciesurgencyaccountancygloommagnetmetallicmasteryvacancyguiltsecrecyText A：Language focus：mentioneddeterminegainedresponsible::Word building Practice1Word building Practice2 Banked clozeheavilyartisticoppositeanalyticaldistortedstumpedText A:Language focus:Expressions in usewere dripping within exchange forflared upmake an analogy betweenset a date formake??out ofmade a pacthad appealed toText AiTranslation:Task1亚里士多德是古希腊的哲学家和科学家。
他的作品涵盖了许多学科，包括物理学、生物学、动物学、逻辑学、伦理学、诗歌、戏剧、音乐、语言学、政治和政府，构成了第一个综合的西方哲学体系。
亚里士多德是第一个将人类的知识领域划分为不同学科的人，如数学,生物学和伦理学。
瞬态电子技术的发展
瞬态电子技术的发展摘要：瞬态电子概念的提出颠覆了人类对传统意义上电子器件认识，发展瞬态电子器件的制备技术，使器件在使用时保持结构与性能的稳定，在需要时能在外界某种条件的触发下实现器件降解，逐渐成为行业内的研究热点。
本文对瞬态电子技术的研究与发展进行了简要介绍。
关键词：瞬态电子、可降解、半导体基金资助：吉林建筑大学大学生创新创业训练计划项目S2021101911291引言传统电子功能器件的研制工作致力于实现器件性能在较长时间内的高稳定性，包括器件的物理寿命和功能状态，现代硅电子的显著特点是可以保持性能与物理形态的不变，几乎可以无限期使用。
新兴的瞬态电子器件是指当所制备的电子功能器件在完成指定功能后，可以在外界刺激触发下, 电子器件的物理形态和功能立即发生部分消失或者完全消失的一种新兴电子器件制备技术。
瞬态电子概念的提出颠覆了人类对传统意义上电子器件认识, 同时, 瞬态电子器件对半导体加工工艺、材料合成等多方面提出新的要求，如何实现瞬态电子器件的制备，使器件在使用时保持结构与性能的稳定，在需要时能在外界某种条件的触发下实现器件降解，逐渐成为行业内的研究热点。
瞬态电子器件在环境保护和植入式医疗领域具有巨大的应用前景，使用生物可溶性材料所开发的电子元器件，在其功能完成之后可“消失”（如溶解于溶剂中），便于将电路上的电子元件回收，能够解决日益增长的电子垃圾污染问题；此外，可以将生物可溶性材料制作的电子设备植入到人体，在完成其功能后自行溶解，无需二次手术，既能减轻病人的痛苦，还能减少医疗资源的浪费。
利用并发展可降解、可再生、环境友好、低毒性的材料来制造安全电子器件、可消失环境传感器和零废物消费电子器件等，有着非常重要的意义。
2技术发展历程2012年，S. W. Hwang等人[1]提出了“瞬态电子器件”的概念，并设计了一种物理瞬态的硅基电子器件，器件在设定时间内稳定工作，达到设定时间点后可完全通过人体（如：血液）溶解，不用再做二次手术。
锂离子电池硅薄膜电极充电膨胀的有限元仿真及其实验验证
锂离子电池硅薄膜电极充电膨胀的有限元仿真及其实验验证季家磊;朱孔军;刘鹏程;钱国明;王裕;刘劲松【摘要】硅基负极锂离子电池材料因其具有高的理论容量(4200m Ah/g)而成为最有希望的高容量负极材料之一.但硅负极在充放电过程中的体积效应,将引起电极材料粉化以及循环性能变差.为解决上述问题,将硅与惰性过渡金属材料复合,过渡金属充当体积效应的缓冲层.本文利用有限元软件abaqus对比了三种不同的硅薄膜材料(Si/Si-M n/Si-Zr).通过磁控溅射方法制备了上述三种硅薄膜材料,并对其进行了SEM、XRD、循环性能等测试,实验得出的结论与仿真结果一致,加入的过渡金属材料有利于缓解体积效应,且Mn材料的缓解效应更强.%Si is the most promising anode material for high energy lithium ion battteries because of its high specific capacity(4200mAh·g -1).But its undesirable volume enpansion results in me-chanical degration and capacity reduction.It is a promising way to combine Si and inert metal to relieve the expansion duringLi+insertion/extraction.In this article,use Abaqus to compare three different Si thin films(Si,Si-Mn,Si-Zr).Si thin film was deposited on Cu foil by magne-tron supttering for use as lithium ion battery anode material.The electrochemical performance of Si film was investgated by cyclic voltammetry and constant current charge/discharge test.The results consistent with simulation.The use of metal material is useful for the electronical per-formance and Zr is more useful than M n.【期刊名称】《电池工业》【年(卷),期】2017(021)006【总页数】9页(P19-27)【关键词】锂离子电池;硅薄膜负极;惰性金属;Abaqus;磁控溅射【作者】季家磊;朱孔军;刘鹏程;钱国明;王裕;刘劲松【作者单位】南京航空航天大学航空宇航学院,江苏南京 210016;南京航空航天大学航空宇航学院,江苏南京 210016;广州大学机械与电子工程学院,广东广州510006;南京航空航天大学航空宇航学院,江苏南京 210016;南京航空航天大学材料科学与工程学院,江苏南京 210016;南京航空航天大学材料科学与工程学院,江苏南京 210016【正文语种】中文【中图分类】TM910.21 IntroductionDue to their advantages of high energy density, long life, low toxicity and environmental friendliness, lithium-ion batteries(LIBs) have become the most promising and widely applied rechargeable batteries.[1] LIBs have been widely used in portable electronics such as mobile phone, digital camera, DV, laptop, and (hybrid) electrical vehicles. The theoretical capacity of commercial graphite (used as anode) is only 372mAh/g[2], and can not meet the increasing demands for lithium-ion batteries with high energy density and long cycling life. In recent years, the development of new high capacity anode material has attracted significant interest. It is well known that some elements can electrochemical react with Li with high capacity.Some alloying elements with high theoretical capacities, such as Si, Sn, Ge Al[3-6], and conversion electrodes such as NiO, and Co3O4[7-8],have been studied extensively. Among these material, Si has high theoretical capacity,4100mAh/g, ten times of graphite[9]. However, Si shows a massive volume expansion/contraction during Li+ insertion/extraction, larger than 300% after fullly lithium insertion[10]. This causes the pulverization of Si particle and loose contacts between Si particles and current collector, which will further result in mechanical in mechanical instability and poor cyclability[11-13]. To solve such problems, combine Si and inert metal materials which can relieve the huge volume change of Si thin films during lithiation and delithiation. Researchers have made attempts to improve the electrochemical performance of Si thin films as anode material, among which, the introduction of a secondary material is an effective way[14-16].In this study, choose secondary materials which have good conductivity and ductility and act as buffer to alleviate the particle pulverization. Use Abaqus to compare the stree and strain in three different thin films(Si, Si-Mn, Si-Zr) during Li+ insertion/extraction and analyse the role of the inert metal. Then, fabricate above Si thin films by magnetron supttering. The electrochemical performance of Si film was investgated by cyclic voltammetry and constant current charge/discharge test. The experimental results consist with the simulation. The use of metal material is useful for the cycling performance and Mn is more useful.2 Finite Element ModelLi+ insertion will result in a distorted lattice, volumetric expansion, mechanical stresss occures because of the constraint of Cu substrate. The size and stiffness of the substrate(Cu foil) is much lower than Si thin film, the deformation of Cu foil is then much lower than Si thin film and can be neglected, we assume the substrate to be rigid. Cracking and interface debonding are not considered, body force and inertia effects are neglected. Mechaniacl deformaion is thought to be quasi-static because it is much slower than diffusion process.An axisymetric finite element model under a cylindrical polar coordinate system(r,θ,z) is used in Abaqus. Si thin film is assumed to be homogeneous and isotropic and be firmly bonded to the rigid substate. Because mechanical stress and diffusion process influence each other, fully coupled thermal-mechanical transient analysis procedure is used. First-order elements are used for the highly nonliner problem, finite element size is set to 1% of the height of Si thin film and fine mesh is used due to stress concentration. To improve convergence of the nonliner problem, liner search algorithm and maximum 5 interations are used.There is no diffusion-stress aanalysis in Abaqus,use the method proposed by Prussin[17] as convention. Mechanical response under concetration loading is analogous to that under temperature loading, stress caused by diffusion is analogous to thermal stress.Extending the 1D relation given by Prussin[17] to 3D, the constitutive equation for diffudsion-induced deformation of an elastic solid can be expressed(1)Fig.1 Structure of thin filmwhere εij(i,j=1,2,3) are componts of strain tensor; σij(i,j=1,2,3) are componts of stress tensor; c(mol m3) is concentration of diffusion componts; Ω is partial molar volume representing v olume expansion caused by diffusion of Li+; E is elastic modulus; υ is posson’s ratio. Stress caused by diffusion is analogous to that caused by temperature gradient, Ω/3 plays the same role as thermal expansion coefficient in thermal stress analysis.2.1 Structure and MaterialThe model of anode is based on the 2016-type cell which is used to be tested later. The anode of 2016-type cell is wafer thin film The thickness and radius of the Si thin film is D and R, the thickness of transition metal material is d. According to 2016-type cell, R is set to be 6μm. BourderauS[18] fabricated the Si thin film with 1.2μm which had bad cycling performance, while thin film with 275nm[19] had better cycling performance, thus D is set to be 500nm. Transition metal just works as buffer layer and not participate in LI+ insertion/extraction, d is smaller than Si and set to be 200nm(Fig. 1.).Based on volumes of lithiated silicon at different Li-Si alloy phases[20], and linear relations between Li fraction and elastic constants[21- 22], dependence of elastic constants on concentration c (fmol mm-3) is expressed.E=E0+k1 c，υ=υ0+k2 c.(2)Where E0=130Gpa, V0=0.22[23]. k1= -0.13Gpa.μm3fmol-1，k2=-0.00047μm3fmol-1(minus k1、k2 represents the soften of Si electrode during lithium intercalation.)The choice of transition metal must have good ductility, it acts as the buffer to alleviate the huge expansion, at the same time, it doesn’t act with Li+. Metal choosed here is Mn and Zr.2.2 Boundary ConditionAs metioned previous,the structure of the electrode is wafer type and symmetry, also the electrode is surrounded by invariant Li-ion concentration,the electrod can be treated as a symmetric finite model, and for simplify, we choose a section for analysis.The initial condition iswhen t=0, c=0.(3)In potentiostatic operation,the electrode surfaces are surrounded by an invariant Li-ion concentration, cs, so the concentration of Li-ion on the top surface and edge surface is fixed.when 0<t<t1, r=R, c=cs.(4)when 0<t<t1, z=h, c=cs.(5)Cu foil is rigid substrate and doesn’t take part in Li+ diffusion,(6)Under the cylindrical polar coordinate system, the structure, boundary conditions and loading conditions are all axisymmetric.when t>0,r=0, ur=0.(7)Volume change consistsin stress because of the constraint of substrate. Because the film is firmly adherent to the substrate, there is no lateral displacements occures on the interface.when t>0,z=0,ur=uθ=uz=0.(8)There is no mechanical loading applied on the top surface and side sur face.when t>0,在z=h处,σz=0.(9)when t>0, r=R, z>0, σr=0.(10)3 Simulation Results3.1 Concentratin, Displacement and Stress FieldsThe concentration field before fully insertion is showed in Fig. 2a. Due to the edge diffusion, concention is dependent on radial coordinate. For the central region of the electrode, concentration is dependent on axial displacement.The displacement and stress field after fully insertion is showed in Fig. 2b-e.Fig. 2d-e. shows the expansion caused by lithium-ion insertion includes radial extension and bending.The radial displacement is concentrated at the edge of the top surface and the maximum radial displacement occures at the edge on the top surface, also there is little radial displacement in the central region of the film.The maximum axial displacement occures at the center of the top surface. Axial displacement in the central region can be regarded to be independent of radial coordinate. Due to the fixed constraint of the rigid substrate, negative axial displacement is possible near the edge on the interface. A dome-like morphology is formed due to the axial and lateral expansions.Fig.2 Concentration, displacemt and stress fields (a.concentration field, b.stress field, c, d, e. displacement field in equilibrium state) Fig.2b shows the stress caused by lithium-ion insertion mainly occures at the center of the top surface and the edge of the bottom surface.3.2 ComparasionofDisplacement/StressFieldsinDifferentSi-MThinFilms The displacement after fully insertion is showed in Fig.3. The distribution of displacement in different Si-M electrode is similar. No matter the total displacement or vertional/radial displacement declines while the metal is used.Same conclusion can be achieved in the stress fields (Fig. 4). The maximun of von mises of Si-M thin film is less than Si thin film. Both the results of displacement and stress comparasion fields reveals that use of metal is beneficial to the Si anode to experience less destroy during insertion.Fig.3 Comparasion of displacement fields (a.total, b.radial, c.axial displacement)Fig. 4 Comparasion of stress fields(a.Si, b.Si-Mn,c.Si-Zr)4 Experimental Results4.1 ExperimentalSi thin films were prepared in an PVD 75 multi-target magnetron sputtering system(KJLC, Co.). The samples were deposited on both Si wafer for thickness measurement and Cu foil for electrochemical measurements. The target was N-type monocrystalline Si with 2 inch diameters and 99.999% purity, Mn with 99.9% purity and Zr with 99.5% purity. The target-substrate distance of the sputtering system was set to be 50mm. After the base pressure reached 8.3×10-4 Pa, Ar (99.999%) was introduced into the chamber. The working pressure was kept at 8mtorr. Si thin films were deposited using a constant radio frequency power supply of 100W.Thefilm thickness was controlled by deposition time.The amount of deposited Si was calculated assuming a density of 2.33g·cm-3 for the Si thin film.The morphology and accurate thickness of Si thin films were measured by the field emission scanning electron microscopy (FSEM, SIGMA, Germany). The phase structure of was analyzed by X-ray diffraction (XRD, Bruker D8 Advance, Germany).To evaluate the electrochemical properties of the Si thin film anode, 2025-type half-cells were assembled in an argon-filled glove box with H2O andO2 concentrations of less than 1ppm. A lithium metal foil was used as a counter electrode, and Celgard2400 was used as a separator. Theelectrolyte solution was 1.0 M LiPF6 in EC/DEC (1∶1 vol/vol). Cyclic voltammetry measurements were performed using an electrochemical workstation (Princeton PARSTAT MC) at a scan rate of 0.01 mV in the potential range 0V～1.5V.Galvanostatic charge/discharge measurement was carried out using a Land battery test system (LAND CT2001A) with the cut off potentials being 0V versus Li/Li+ for discharge and 1.5V versusLi/Li+ for charge.4.2 Results and DiscussionFig.5 SEM images(a.cross-ssection, subface of b.Si, c. Si-Mn, d. Si-Zr)The cross-sectional SEM image of Si thin film deposited on a Si wafer is presented in Fig. 5a. The thickness of the dense Si、Mn、Zr can be observed,and the corresponding growth rate can be calculated,finally actual operating time was obtained accoring to the target thickness(Tab 1). Table1SputteringParameterTargetSiMnZrPower(W)100100100Time(min)606030Th ickness(nm)320200170Rate(nm/min)5．33．35．7TargetThickness(nm)500 200200ActualTime(min)946035Fig.6. shows the XRD pattern of Si thin film deposited on Cu foil. All the diffraction peaks are attributed to the Cu foil, and no peak of Si appears, especially the typical peak for crystal Si at 28°. This indicates that the Si thin film is amorphous.Fig.6 XRD patterns of Si thin filmsThe L+ insertion/extraction reactions of Si thin film were studied by cyclic voltammetry. For all of the three thin films, three cyclic voltammetriccurves of the Si thin film are shown in Fig. 7. In the first scanning cycle, there is a cathodic peak at 0.32V, which disappears from the second cycle. This cathodic peak is attributed to the formation of a solid electrolyte interphase (SEI) layer due to decomposition of electrolyte on the film surface. Two cathodic peaks at 0.20V and 0.05V, as well as two anodic peaks at 0.50V and 0.33V, are observed on all three cyclic voltammograms; these are ascribed to the electrochemical reactions of Li+ insertion and extraction in the Si thin film. The slight difference in the intensity and the potential for each peak can be attributed to the kinetic effect involved in the cyclic voltammetry measurement.Fig.7 Cyclic voltammetry plots (scanning rate 0.1Mv/s，potential range0V～1.5V, a. Si; b.Si-Mn; c.Si-Zr)Fig.8.shows the first three times of the discharge/charge curves. The first discharge capacity of the Si, Si-Mn, Si-Zr thin film is 2045.0mAh·g-1, 2203.1mAh·g-1, 2505.0mAh·g-1, and initial coulombic efficiency is 101.76%, 103.98%, 102.89%. The first and second reversible capacity of the Si-Mn thin film is 1900.3mAh·g-1 and 1976.0mAh g-1，for Si-Zr, 1997.0mAh·g-1, 2054.7mAh·g-1,which is much larger than that of a graphiteanod e(1662.9mAh·g-1, 1692.3mAh· g-1,respectively). The irreversible capacity is attributed to the formation of a SEI layer in the first cycle. In evidence, a SEI-formation voltage plateau is observed near 0.32V, which disappears in the second cycle. This observation is also in good agreement with CV results.Fig.8 Discharge/charge curves (a. Si; b.Si-Mn; c.Si-Zr)Cycling performance of the Si thin films are shown in Fig. 9 a-c. The first reversible capacity 100mA/g for Si, Si/Mn, Si/Zr is 1692.3mAh/g,1830.8mAh/g, 1955.6mAh/g respectively, and 71.2%, 83.9%, 88.2% capacity remained after 50 cycles.The introduce of transition metal can enhance both the first reversible capacity and the capacity retention effectively, which proves that the metal can improve the cycling performance of Si thin films. Rate performance of the Si thin films are shown in Fig. 9 d-f.Fig.9 Eletronical performance of Si thin films (Cycling performance of a.Si, b. Si-Mn, c. Si-Zr, rate performance of d. Si, e. Si-Mn, f. Si-Zr)To further evaluate the performance of Si thin films, the rate capability measurements (Fig. 9d-f) at the quickly increased current density from 0.1A/g to 1A/g were carried out. For Si thin films, the discharge capacity of 2045.3mAh/g, 1413.2mAh/g, 1128.8mAh/g, 919.5mAh/g, 732.7mAh/g can be obtained at 0.1A/g, 0.2A/g, 0.3A/g, 0.5A/g, 1.0A/g, 0.1A/g. For Si-Mn, 2203.1mAh/g, 1718.9mAh/g, 1535.7mAh/g, 1329.6mAh/g, 1044.3mAh/g can be obtained, and for Si/Zr, 2505.0mAh/g, 1859.4mAh/g, 1661.2mAh/g, 1500.6mAh/g, 1117.8mAh/g can be delievered. Although suffering from the rapid change of the current density, the cell can still exhibit a stable cycling at each current. Importantly, 80% of the first reversible capacity can be remained for Si thin film when the current density is turned back to1A/g, and for Si-Mn, Si-Zr, 89.0% and 92.9% can be remained.It proved that use of metal is beneficial to the electrocal performance again.5 ConclusionIn this article, Si and inert metal is combined to relieve the expansion during Li+ insertion/ extraction. Use Abaqus to compare three different Si thin films (Si, Si-Mn, Si-Zr).we found that the use of inert metal reduces the displacement and stress induced during the Li+ insertion. Also, Si-M thin film used as anode material.was deposited by magnetron supttering The morphology of the Si-M thin films are similar, and XRD results reveals that the structure of Si thin films is amorphous. The electrochemical performance of Si thin films consistents with the simulation, use of metal can relieve the expansion and result in better cycling and rate performance. Among Mn and Zr, Mn is more useful.References：【相关文献】[1] Goodenough J B, Park K S, The Li-ion Rechargeable Battery: A Perspective[J],American Chemical Society, Journal,2013. 135(4):1167-76.[2] Wachtler M, Besenhard J O, Winter M, Tin and tin-based intermetallics as new anode materials for lithium-ion cells[J], Journal of Power Sources, 2001 , 94 (2) :189-193.[3] Obrovac M N, Krause L J, Reversible Cycling of Crystalline Silicon Powder[J],Journal of the Electrochemical Society, 2007,154 (2) :A103-A108.[4] Graetz J, Ahn C C, Yazami R, and Fultz B, Nanocrystalline and Thin Film Germanium Electrodes with High Lithium Capacity and High Rate Capabilities[J], 2004, 151 (5): A698-A702.[5] Wolfenstine J,Foster D,Read J, Behl W K, and Luecke W, Experimental confirmation of the model for microcracking during lithium charging in single-phase alloys[J], Journal of Power Sources, 2000 , 87 (1-2) :1-3.[6] Liu Y, Hudak N S, Huber D L, Limmer S J, Sullivan J P, and Huang J Y, In situ transmission electron microscopy observation of pulverization of aluminum nanowiresand evolution of the thin surface Al2O3 layers during lithiation-delithiation cycles[J], Nano Letters, 2011, 11 (10) :4188.[7] Wang Y, Qin Q Z, A Nanocrystalline NiO Thin-Film Electrode Prepared by Pulsed Laser Ablation for Li-Ion Batteries[J], Journal of the Electrochemical Society, 2002,149 (7):A873-A878.[8] Fu Z W, Wang Y, Zhang Y, and Qin Q Z, Electrochemical reaction of nanocrystallineCo3O4, thin film with lithium[J], Solid State Ionics, 2004,170:105-109.[9] Huggins R A, Advanced batteries: Materials science aspects[M], SpringerBerlin, 2009.[10] Lee S J, Lee J K, Chung S H, Lee H Y, Lee S M, and Baik H K, Stress effect on cycle properties of the silicon thin-film anode[J],Journal of Power Sources, 2001, 97: 191-193. [11] Winter M, Besenhard J O, ChemInform Abstract: Electrochemical Lithiation of Tin and Tin‐Based Intermetallics and Composites[J], Electrochimica Acta, 1999. 45:31-50.[12] Yoshio M, Tsumura T, Dimov N, Electrochemical behaviors of silicon based anode material[J], Journal of Power Sources, 2006 , 153 (2) :375-379.[13] Wang D Y, Wu X D, Wang Z X, and Chen L Q, Cracking causing cyclic instability of lifepo 4, cathode material[J], Journal of Power Sources, 2005, 140 (1) :125-128.[14] Datta M K, Maranchi J, Chung S J, Epur R, Kadakia K, and Jampani P, Amorphous silicon-carbon based nano-scale thin film anode materials for lithium ion batteries[J], Electrochimica Acta, 2011, 56 :4717-4723.[15] Zhou Y N, Li W J, Chen H J, Liu C, Zhang L, and Fu Z, Nanostructured nisi thin films asa new anode material for lithium ion batteries[J], Electrochemistry Communications, 2011,13 (6) :546-549.[16] Imai Y, Watanabe A, Energetics of compounds related to Mg 2 Si as an anode material for lithium-ion batteries using first principle calculations[J], Journal of Alloys & Compounds, 2011, 509 (30) :7877-7880.[17] Prussin S, Generation and Distribution of Dislocations by Solute Diffusion[J], Journal of Applied Physics, 1961 ,32(10):1876-1881.[18] Bourderau S, Brousse T, Schleich D M, Amorphous silicon as a possible anode material for Li-ion batteries[J], Journal of Power Sources, 1999 ,81-82 (9) :233-236. 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热红外传感史
History of infrared detectorsA.ROGALSKI*Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str.,00–908 Warsaw, PolandThis paper overviews the history of infrared detector materials starting with Herschel’s experiment with thermometer on February11th,1800.Infrared detectors are in general used to detect,image,and measure patterns of the thermal heat radia−tion which all objects emit.At the beginning,their development was connected with thermal detectors,such as ther−mocouples and bolometers,which are still used today and which are generally sensitive to all infrared wavelengths and op−erate at room temperature.The second kind of detectors,called the photon detectors,was mainly developed during the20th Century to improve sensitivity and response time.These detectors have been extensively developed since the1940’s.Lead sulphide(PbS)was the first practical IR detector with sensitivity to infrared wavelengths up to~3μm.After World War II infrared detector technology development was and continues to be primarily driven by military applications.Discovery of variable band gap HgCdTe ternary alloy by Lawson and co−workers in1959opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design.Many of these advances were transferred to IR astronomy from Departments of Defence ter on civilian applications of infrared technology are frequently called“dual−use technology applications.”One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies,as well as the noticeable price decrease in these high cost tech−nologies.In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays(FPAs).Development in FPA technology has revolutionized infrared imaging.Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.Keywords:thermal and photon detectors, lead salt detectors, HgCdTe detectors, microbolometers, focal plane arrays.Contents1.Introduction2.Historical perspective3.Classification of infrared detectors3.1.Photon detectors3.2.Thermal detectors4.Post−War activity5.HgCdTe era6.Alternative material systems6.1.InSb and InGaAs6.2.GaAs/AlGaAs quantum well superlattices6.3.InAs/GaInSb strained layer superlattices6.4.Hg−based alternatives to HgCdTe7.New revolution in thermal detectors8.Focal plane arrays – revolution in imaging systems8.1.Cooled FPAs8.2.Uncooled FPAs8.3.Readiness level of LWIR detector technologies9.SummaryReferences 1.IntroductionLooking back over the past1000years we notice that infra−red radiation(IR)itself was unknown until212years ago when Herschel’s experiment with thermometer and prism was first reported.Frederick William Herschel(1738–1822) was born in Hanover,Germany but emigrated to Britain at age19,where he became well known as both a musician and an astronomer.Herschel became most famous for the discovery of Uranus in1781(the first new planet found since antiquity)in addition to two of its major moons,Tita−nia and Oberon.He also discovered two moons of Saturn and infrared radiation.Herschel is also known for the twenty−four symphonies that he composed.W.Herschel made another milestone discovery–discov−ery of infrared light on February11th,1800.He studied the spectrum of sunlight with a prism[see Fig.1in Ref.1],mea−suring temperature of each colour.The detector consisted of liquid in a glass thermometer with a specially blackened bulb to absorb radiation.Herschel built a crude monochromator that used a thermometer as a detector,so that he could mea−sure the distribution of energy in sunlight and found that the highest temperature was just beyond the red,what we now call the infrared(‘below the red’,from the Latin‘infra’–be−OPTO−ELECTRONICS REVIEW20(3),279–308DOI: 10.2478/s11772−012−0037−7*e−mail: rogan@.pllow)–see Fig.1(b)[2].In April 1800he reported it to the Royal Society as dark heat (Ref.1,pp.288–290):Here the thermometer No.1rose 7degrees,in 10minu−tes,by an exposure to the full red coloured rays.I drew back the stand,till the centre of the ball of No.1was just at the vanishing of the red colour,so that half its ball was within,and half without,the visible rays of theAnd here the thermometerin 16minutes,degrees,when its centre was inch out of the raysof the sun.as had a rising of 9de−grees,and here the difference is almost too trifling to suppose,that latter situation of the thermometer was much beyond the maximum of the heating power;while,at the same time,the experiment sufficiently indi−cates,that the place inquired after need not be looked for at a greater distance.Making further experiments on what Herschel called the ‘calorific rays’that existed beyond the red part of the spec−trum,he found that they were reflected,refracted,absorbed and transmitted just like visible light [1,3,4].The early history of IR was reviewed about 50years ago in three well−known monographs [5–7].Many historical information can be also found in four papers published by Barr [3,4,8,9]and in more recently published monograph [10].Table 1summarises the historical development of infrared physics and technology [11,12].2.Historical perspectiveFor thirty years following Herschel’s discovery,very little progress was made beyond establishing that the infrared ra−diation obeyed the simplest laws of optics.Slow progress inthe study of infrared was caused by the lack of sensitive and accurate detectors –the experimenters were handicapped by the ordinary thermometer.However,towards the second de−cade of the 19th century,Thomas Johann Seebeck began to examine the junction behaviour of electrically conductive materials.In 1821he discovered that a small electric current will flow in a closed circuit of two dissimilar metallic con−ductors,when their junctions are kept at different tempera−tures [13].During that time,most physicists thought that ra−diant heat and light were different phenomena,and the dis−covery of Seebeck indirectly contributed to a revival of the debate on the nature of heat.Due to small output vol−tage of Seebeck’s junctions,some μV/K,the measurement of very small temperature differences were prevented.In 1829L.Nobili made the first thermocouple and improved electrical thermometer based on the thermoelectric effect discovered by Seebeck in 1826.Four years later,M.Melloni introduced the idea of connecting several bismuth−copper thermocouples in series,generating a higher and,therefore,measurable output voltage.It was at least 40times more sensitive than the best thermometer available and could de−tect the heat from a person at a distance of 30ft [8].The out−put voltage of such a thermopile structure linearly increases with the number of connected thermocouples.An example of thermopile’s prototype invented by Nobili is shown in Fig.2(a).It consists of twelve large bismuth and antimony elements.The elements were placed upright in a brass ring secured to an adjustable support,and were screened by a wooden disk with a 15−mm central aperture.Incomplete version of the Nobili−Melloni thermopile originally fitted with the brass cone−shaped tubes to collect ra−diant heat is shown in Fig.2(b).This instrument was much more sensi−tive than the thermometers previously used and became the most widely used detector of IR radiation for the next half century.The third member of the trio,Langley’s bolometer appea−red in 1880[7].Samuel Pierpont Langley (1834–1906)used two thin ribbons of platinum foil connected so as to form two arms of a Wheatstone bridge (see Fig.3)[15].This instrument enabled him to study solar irradiance far into its infrared region and to measure theintensityof solar radia−tion at various wavelengths [9,16,17].The bolometer’s sen−History of infrared detectorsFig.1.Herschel’s first experiment:A,B –the small stand,1,2,3–the thermometers upon it,C,D –the prism at the window,E –the spec−trum thrown upon the table,so as to bring the last quarter of an inch of the read colour upon the stand (after Ref.1).InsideSir FrederickWilliam Herschel (1738–1822)measures infrared light from the sun– artist’s impression (after Ref. 2).Fig.2.The Nobili−Meloni thermopiles:(a)thermopile’s prototype invented by Nobili (ca.1829),(b)incomplete version of the Nobili−−Melloni thermopile (ca.1831).Museo Galileo –Institute and Museum of the History of Science,Piazza dei Giudici 1,50122Florence, Italy (after Ref. 14).Table 1. Milestones in the development of infrared physics and technology (up−dated after Refs. 11 and 12)Year Event1800Discovery of the existence of thermal radiation in the invisible beyond the red by W. HERSCHEL1821Discovery of the thermoelectric effects using an antimony−copper pair by T.J. SEEBECK1830Thermal element for thermal radiation measurement by L. NOBILI1833Thermopile consisting of 10 in−line Sb−Bi thermal pairs by L. NOBILI and M. MELLONI1834Discovery of the PELTIER effect on a current−fed pair of two different conductors by J.C. PELTIER1835Formulation of the hypothesis that light and electromagnetic radiation are of the same nature by A.M. AMPERE1839Solar absorption spectrum of the atmosphere and the role of water vapour by M. MELLONI1840Discovery of the three atmospheric windows by J. HERSCHEL (son of W. HERSCHEL)1857Harmonization of the three thermoelectric effects (SEEBECK, PELTIER, THOMSON) by W. THOMSON (Lord KELVIN)1859Relationship between absorption and emission by G. KIRCHHOFF1864Theory of electromagnetic radiation by J.C. MAXWELL1873Discovery of photoconductive effect in selenium by W. SMITH1876Discovery of photovoltaic effect in selenium (photopiles) by W.G. ADAMS and A.E. DAY1879Empirical relationship between radiation intensity and temperature of a blackbody by J. STEFAN1880Study of absorption characteristics of the atmosphere through a Pt bolometer resistance by S.P. LANGLEY1883Study of transmission characteristics of IR−transparent materials by M. MELLONI1884Thermodynamic derivation of the STEFAN law by L. BOLTZMANN1887Observation of photoelectric effect in the ultraviolet by H. HERTZ1890J. ELSTER and H. GEITEL constructed a photoemissive detector consisted of an alkali−metal cathode1894, 1900Derivation of the wavelength relation of blackbody radiation by J.W. RAYEIGH and W. WIEN1900Discovery of quantum properties of light by M. PLANCK1903Temperature measurements of stars and planets using IR radiometry and spectrometry by W.W. COBLENTZ1905 A. EINSTEIN established the theory of photoelectricity1911R. ROSLING made the first television image tube on the principle of cathode ray tubes constructed by F. Braun in 18971914Application of bolometers for the remote exploration of people and aircrafts ( a man at 200 m and a plane at 1000 m)1917T.W. CASE developed the first infrared photoconductor from substance composed of thallium and sulphur1923W. SCHOTTKY established the theory of dry rectifiers1925V.K. ZWORYKIN made a television image tube (kinescope) then between 1925 and 1933, the first electronic camera with the aid of converter tube (iconoscope)1928Proposal of the idea of the electro−optical converter (including the multistage one) by G. HOLST, J.H. DE BOER, M.C. TEVES, and C.F. VEENEMANS1929L.R. KOHLER made a converter tube with a photocathode (Ag/O/Cs) sensitive in the near infrared1930IR direction finders based on PbS quantum detectors in the wavelength range 1.5–3.0 μm for military applications (GUDDEN, GÖRLICH and KUTSCHER), increased range in World War II to 30 km for ships and 7 km for tanks (3–5 μm)1934First IR image converter1939Development of the first IR display unit in the United States (Sniperscope, Snooperscope)1941R.S. OHL observed the photovoltaic effect shown by a p−n junction in a silicon1942G. EASTMAN (Kodak) offered the first film sensitive to the infrared1947Pneumatically acting, high−detectivity radiation detector by M.J.E. GOLAY1954First imaging cameras based on thermopiles (exposure time of 20 min per image) and on bolometers (4 min)1955Mass production start of IR seeker heads for IR guided rockets in the US (PbS and PbTe detectors, later InSb detectors for Sidewinder rockets)1957Discovery of HgCdTe ternary alloy as infrared detector material by W.D. LAWSON, S. NELSON, and A.S. YOUNG1961Discovery of extrinsic Ge:Hg and its application (linear array) in the first LWIR FLIR systems1965Mass production start of IR cameras for civil applications in Sweden (single−element sensors with optomechanical scanner: AGA Thermografiesystem 660)1970Discovery of charge−couple device (CCD) by W.S. BOYLE and G.E. SMITH1970Production start of IR sensor arrays (monolithic Si−arrays: R.A. SOREF 1968; IR−CCD: 1970; SCHOTTKY diode arrays: F.D.SHEPHERD and A.C. YANG 1973; IR−CMOS: 1980; SPRITE: T. ELIOTT 1981)1975Lunch of national programmes for making spatially high resolution observation systems in the infrared from multielement detectors integrated in a mini cooler (so−called first generation systems): common module (CM) in the United States, thermal imaging commonmodule (TICM) in Great Britain, syteme modulaire termique (SMT) in France1975First In bump hybrid infrared focal plane array1977Discovery of the broken−gap type−II InAs/GaSb superlattices by G.A. SAI−HALASZ, R. TSU, and L. ESAKI1980Development and production of second generation systems [cameras fitted with hybrid HgCdTe(InSb)/Si(readout) FPAs].First demonstration of two−colour back−to−back SWIR GaInAsP detector by J.C. CAMPBELL, A.G. DENTAI, T.P. LEE,and C.A. BURRUS1985Development and mass production of cameras fitted with Schottky diode FPAs (platinum silicide)1990Development and production of quantum well infrared photoconductor (QWIP) hybrid second generation systems1995Production start of IR cameras with uncooled FPAs (focal plane arrays; microbolometer−based and pyroelectric)2000Development and production of third generation infrared systemssitivity was much greater than that of contemporary thermo−piles which were little improved since their use by Melloni. Langley continued to develop his bolometer for the next20 years(400times more sensitive than his first efforts).His latest bolometer could detect the heat from a cow at a dis−tance of quarter of mile [9].From the above information results that at the beginning the development of the IR detectors was connected with ther−mal detectors.The first photon effect,photoconductive ef−fect,was discovered by Smith in1873when he experimented with selenium as an insulator for submarine cables[18].This discovery provided a fertile field of investigation for several decades,though most of the efforts were of doubtful quality. By1927,over1500articles and100patents were listed on photosensitive selenium[19].It should be mentioned that the literature of the early1900’s shows increasing interest in the application of infrared as solution to numerous problems[7].A special contribution of William Coblenz(1873–1962)to infrared radiometry and spectroscopy is marked by huge bib−liography containing hundreds of scientific publications, talks,and abstracts to his credit[20,21].In1915,W.Cob−lentz at the US National Bureau of Standards develops ther−mopile detectors,which he uses to measure the infrared radi−ation from110stars.However,the low sensitivity of early in−frared instruments prevented the detection of other near−IR sources.Work in infrared astronomy remained at a low level until breakthroughs in the development of new,sensitive infrared detectors were achieved in the late1950’s.The principle of photoemission was first demonstrated in1887when Hertz discovered that negatively charged par−ticles were emitted from a conductor if it was irradiated with ultraviolet[22].Further studies revealed that this effect could be produced with visible radiation using an alkali metal electrode [23].Rectifying properties of semiconductor−metal contact were discovered by Ferdinand Braun in1874[24],when he probed a naturally−occurring lead sulphide(galena)crystal with the point of a thin metal wire and noted that current flowed freely in one direction only.Next,Jagadis Chandra Bose demonstrated the use of galena−metal point contact to detect millimetre electromagnetic waves.In1901he filed a U.S patent for a point−contact semiconductor rectifier for detecting radio signals[25].This type of contact called cat’s whisker detector(sometimes also as crystal detector)played serious role in the initial phase of radio development.How−ever,this contact was not used in a radiation detector for the next several decades.Although crystal rectifiers allowed to fabricate simple radio sets,however,by the mid−1920s the predictable performance of vacuum−tubes replaced them in most radio applications.The period between World Wars I and II is marked by the development of photon detectors and image converters and by emergence of infrared spectroscopy as one of the key analytical techniques available to chemists.The image con−verter,developed on the eve of World War II,was of tre−mendous interest to the military because it enabled man to see in the dark.The first IR photoconductor was developed by Theodore W.Case in1917[26].He discovered that a substance com−posed of thallium and sulphur(Tl2S)exhibited photocon−ductivity.Supported by the US Army between1917and 1918,Case adapted these relatively unreliable detectors for use as sensors in an infrared signalling device[27].The pro−totype signalling system,consisting of a60−inch diameter searchlight as the source of radiation and a thallous sulphide detector at the focus of a24−inch diameter paraboloid mir−ror,sent messages18miles through what was described as ‘smoky atmosphere’in1917.However,instability of resis−tance in the presence of light or polarizing voltage,loss of responsivity due to over−exposure to light,high noise,slug−gish response and lack of reproducibility seemed to be inhe−rent weaknesses.Work was discontinued in1918;commu−nication by the detection of infrared radiation appeared dis−tinctly ter Case found that the addition of oxygen greatly enhanced the response [28].The idea of the electro−optical converter,including the multistage one,was proposed by Holst et al.in1928[29]. The first attempt to make the converter was not successful.A working tube consisted of a photocathode in close proxi−mity to a fluorescent screen was made by the authors in 1934 in Philips firm.In about1930,the appearance of the Cs−O−Ag photo−tube,with stable characteristics,to great extent discouraged further development of photoconductive cells until about 1940.The Cs−O−Ag photocathode(also called S−1)elabo−History of infrared detectorsFig.3.Longley’s bolometer(a)composed of two sets of thin plati−num strips(b),a Wheatstone bridge,a battery,and a galvanometer measuring electrical current (after Ref. 15 and 16).rated by Koller and Campbell[30]had a quantum efficiency two orders of magnitude above anything previously studied, and consequently a new era in photoemissive devices was inaugurated[31].In the same year,the Japanese scientists S. Asao and M.Suzuki reported a method for enhancing the sensitivity of silver in the S−1photocathode[32].Consisted of a layer of caesium on oxidized silver,S−1is sensitive with useful response in the near infrared,out to approxi−mately1.2μm,and the visible and ultraviolet region,down to0.3μm.Probably the most significant IR development in the United States during1930’s was the Radio Corporation of America(RCA)IR image tube.During World War II, near−IR(NIR)cathodes were coupled to visible phosphors to provide a NIR image converter.With the establishment of the National Defence Research Committee,the develop−ment of this tube was accelerated.In1942,the tube went into production as the RCA1P25image converter(see Fig.4).This was one of the tubes used during World War II as a part of the”Snooperscope”and”Sniperscope,”which were used for night observation with infrared sources of illumination.Since then various photocathodes have been developed including bialkali photocathodes for the visible region,multialkali photocathodes with high sensitivity ex−tending to the infrared region and alkali halide photocatho−des intended for ultraviolet detection.The early concepts of image intensification were not basically different from those today.However,the early devices suffered from two major deficiencies:poor photo−cathodes and poor ter development of both cathode and coupling technologies changed the image in−tensifier into much more useful device.The concept of image intensification by cascading stages was suggested independently by number of workers.In Great Britain,the work was directed toward proximity focused tubes,while in the United State and in Germany–to electrostatically focused tubes.A history of night vision imaging devices is given by Biberman and Sendall in monograph Electro−Opti−cal Imaging:System Performance and Modelling,SPIE Press,2000[10].The Biberman’s monograph describes the basic trends of infrared optoelectronics development in the USA,Great Britain,France,and Germany.Seven years later Ponomarenko and Filachev completed this monograph writ−ing the book Infrared Techniques and Electro−Optics in Russia:A History1946−2006,SPIE Press,about achieve−ments of IR techniques and electrooptics in the former USSR and Russia [33].In the early1930’s,interest in improved detectors began in Germany[27,34,35].In1933,Edgar W.Kutzscher at the University of Berlin,discovered that lead sulphide(from natural galena found in Sardinia)was photoconductive and had response to about3μm.B.Gudden at the University of Prague used evaporation techniques to develop sensitive PbS films.Work directed by Kutzscher,initially at the Uni−versity of Berlin and later at the Electroacustic Company in Kiel,dealt primarily with the chemical deposition approach to film formation.This work ultimately lead to the fabrica−tion of the most sensitive German detectors.These works were,of course,done under great secrecy and the results were not generally known until after1945.Lead sulphide photoconductors were brought to the manufacturing stage of development in Germany in about1943.Lead sulphide was the first practical infrared detector deployed in a variety of applications during the war.The most notable was the Kiel IV,an airborne IR system that had excellent range and which was produced at Carl Zeiss in Jena under the direction of Werner K. Weihe [6].In1941,Robert J.Cashman improved the technology of thallous sulphide detectors,which led to successful produc−tion[36,37].Cashman,after success with thallous sulphide detectors,concentrated his efforts on lead sulphide detec−tors,which were first produced in the United States at Northwestern University in1944.After World War II Cash−man found that other semiconductors of the lead salt family (PbSe and PbTe)showed promise as infrared detectors[38]. The early detector cells manufactured by Cashman are shown in Fig. 5.Fig.4.The original1P25image converter tube developed by the RCA(a).This device measures115×38mm overall and has7pins.It opera−tion is indicated by the schematic drawing (b).After1945,the wide−ranging German trajectory of research was essentially the direction continued in the USA, Great Britain and Soviet Union under military sponsorship after the war[27,39].Kutzscher’s facilities were captured by the Russians,thus providing the basis for early Soviet detector development.From1946,detector technology was rapidly disseminated to firms such as Mullard Ltd.in Southampton,UK,as part of war reparations,and some−times was accompanied by the valuable tacit knowledge of technical experts.E.W.Kutzscher,for example,was flown to Britain from Kiel after the war,and subsequently had an important influence on American developments when he joined Lockheed Aircraft Co.in Burbank,California as a research scientist.Although the fabrication methods developed for lead salt photoconductors was usually not completely under−stood,their properties are well established and reproducibi−lity could only be achieved after following well−tried reci−pes.Unlike most other semiconductor IR detectors,lead salt photoconductive materials are used in the form of polycrys−talline films approximately1μm thick and with individual crystallites ranging in size from approximately0.1–1.0μm. They are usually prepared by chemical deposition using empirical recipes,which generally yields better uniformity of response and more stable results than the evaporative methods.In order to obtain high−performance detectors, lead chalcogenide films need to be sensitized by oxidation. The oxidation may be carried out by using additives in the deposition bath,by post−deposition heat treatment in the presence of oxygen,or by chemical oxidation of the film. The effect of the oxidant is to introduce sensitizing centres and additional states into the bandgap and thereby increase the lifetime of the photoexcited holes in the p−type material.3.Classification of infrared detectorsObserving a history of the development of the IR detector technology after World War II,many materials have been investigated.A simple theorem,after Norton[40],can be stated:”All physical phenomena in the range of about0.1–1 eV will be proposed for IR detectors”.Among these effects are:thermoelectric power(thermocouples),change in elec−trical conductivity(bolometers),gas expansion(Golay cell), pyroelectricity(pyroelectric detectors),photon drag,Jose−phson effect(Josephson junctions,SQUIDs),internal emis−sion(PtSi Schottky barriers),fundamental absorption(in−trinsic photodetectors),impurity absorption(extrinsic pho−todetectors),low dimensional solids[superlattice(SL), quantum well(QW)and quantum dot(QD)detectors], different type of phase transitions, etc.Figure6gives approximate dates of significant develop−ment efforts for the materials mentioned.The years during World War II saw the origins of modern IR detector tech−nology.Recent success in applying infrared technology to remote sensing problems has been made possible by the successful development of high−performance infrared de−tectors over the last six decades.Photon IR technology com−bined with semiconductor material science,photolithogra−phy technology developed for integrated circuits,and the impetus of Cold War military preparedness have propelled extraordinary advances in IR capabilities within a short time period during the last century [41].The majority of optical detectors can be classified in two broad categories:photon detectors(also called quantum detectors) and thermal detectors.3.1.Photon detectorsIn photon detectors the radiation is absorbed within the material by interaction with electrons either bound to lattice atoms or to impurity atoms or with free electrons.The observed electrical output signal results from the changed electronic energy distribution.The photon detectors show a selective wavelength dependence of response per unit incident radiation power(see Fig.8).They exhibit both a good signal−to−noise performance and a very fast res−ponse.But to achieve this,the photon IR detectors require cryogenic cooling.This is necessary to prevent the thermalHistory of infrared detectorsFig.5.Cashman’s detector cells:(a)Tl2S cell(ca.1943):a grid of two intermeshing comb−line sets of conducting paths were first pro−vided and next the T2S was evaporated over the grid structure;(b) PbS cell(ca.1945)the PbS layer was evaporated on the wall of the tube on which electrical leads had been drawn with aquadag(afterRef. 38).。
维沙耐电子Vishay Siliconix S17-1349-Rev. A N-Channel 20
N-Channel 200 V (D-S) MOSFETFEATURES•ThunderFET technology optimizes balance of R DS(on), Q g , Q sw , and Q oss •100 % R g and UIS tested•Material categorization:for definitions of compliance please see /doc?99912APPLICATIONS•Fixed telecom •DC/DC converter•Primary and secondary side switch •Synchronous rectificationNotesa.T C = 25 °Cb.Surface mounted on 1" x 1" FR4 boardc.t = 10 sd.See solder profile (/doc?73257). The PowerPAK SO-8 is a leadless package. The end of the lead terminal is exposed copper (not plated) as a result of the singulation process in manufacturing. A solder fillet at the exposed copper tip cannot be guaranteed and is not required to ensure adequate bottom side solder interconnectione.Rework conditions: manual soldering with a soldering iron is not recommended for leadless componentsf.Maximum under steady state conditions is 65 °C/WPRODUCT SUMMARYV DS (V)200R DS(on) max. (Ω) at V GS = 10 V 0.070RDS(on) max. (Ω) at V GS = 7.5 V 0.080Q g typ. (nC)15I D (A) a17.2ConfigurationSinglePowerPAK ® S O-8 S ingleTop View16.15 mm5.15 m mBottom View4G3S 2S1SD 8D 6D 7D 5ORDERING INFORMATIONPackagePowerPAK SO-8Lead (Pb)-free and halogen-freeSi7172ADP-T1-RE3ABSOLUTE MAXIMUM RATINGS (T A = 25 °C, unless otherwise noted)PARAMETER S YMBOL LIMIT UNITDrain-source voltage V DS200VGate-source voltage V GS ± 20Continuous drain current (T J = 150 °C)T C = 25 °C I D17.2AT C = 70 °C13.8T A = 25 °C 5.3 b, c T A = 70 °C 4.2 b, cPulsed drain current (t = 100 μs)I DM 50Continuous source-drain diode currentT C = 25 °CI S 26T A = 25 °C 4.5 b, cSingle pulse avalanche current L = 0.1 mHI AS 15Single pulse avalanche Energy E AS 11.25mJMaximum power dissipation T C = 25 °C P D 52WT C = 70 °C33T A = 25 °C 5 b, c T A = 70 °C 3.2 b, cOperating junction and storage temperature range T J , T stg -55 to +150°C Soldering recommendations (peak temperature) d, e 260THERMAL RESISTANCE RATINGSPARAMETER S YMBOL TYPICAL MAXIMUM UNITMaximum junction-to-ambient b, ft ≤ 10 s R thJA 2025°C/WMaximum junction-to-case (drain)Steady state R thJC 1.9 2.4Notesa.Pulse test; pulse width ≤ 300 μs, duty cycle ≤ 2 %b.Guaranteed by design, not subject to production testingStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.SPECIFICATIONS (T J = 25 °C, unless otherwise noted)PARAMETER S YMBOL TE S T CONDITION S MIN. TYP.MAX.UNITStaticDrain-source breakdown voltage V DS V GS = 0 V, I D = 250 μA200--V V DS temperature coefficient ∆V DS /T J I D = 250 μA -156-mV/°C V GS(th) temperature coefficient ∆V GS(th)/T J --6.7-Gate-source threshold voltage V GS(th) V DS = V GS , I D = 250 μA 2-4V Gate-source leakageI GSS V DS = 0 V, V GS = ± 20 V --± 100nA Zero gate voltage drain current I DSS V DS = 200 V, V GS = 0 V --1μA V DS = 200 V, V GS = 0 V, T J = 70 °C--10On-state drain current aI D(on) V DS ≥ 5 V, V GS = 10 V 30--A Drain-source on-state resistance a R DS(on) V GS = 10 V, I D = 10 A -0.0500.070ΩV GS = 7.5 V, I D = 10 A -0.0510.080Forward transconductance a g fsV DS = 15 V, I D = 10 A-26-SDynamic bInput capacitance C iss V DS = 100 V, V GS = 0 V, f = 1 MHz -1110-pFOutput capacitanceC oss-100-Reverse transfer capacitance C rss -8.3-Total gate charge Q gV DS = 100 V, V GS = 10 V, I D = 10 A-19.530nC V DS = 100 V, V GS = 7.5 V, I D = 10 A -1523Gate-source charge Q gs - 5.3-Gate-drain charge Q gd - 5.2-Output charge Q oss V DS = 100 V, V GS = 0 V-3654Gate resistance R g f = 1 MHz0.5 1.6 3.0ΩTurn-on delay time t d(on)V DD = 100 V, R L = 10 ΩI D ≅ 10 A, V GEN = 10 V, R g = 1 Ω-918ns Rise timet r-1836Turn-off delay time t d(off) -1632Fall timet f -816Turn-on delay time t d(on)V DD = 100 V, R L = 10 ΩI D ≅ 10 A, V GEN = 7.5 V, R g = 1 Ω-1122Rise timet r -4590Turn-off delay time t d(off) -1530Fall timet f -2346Drain-Source Body Diode Characteristics Continuous source-drain diode current I S T C = 25 °C--26A Pulse diode forward current (t = 100 μs)I SM --50Body diode voltageV SD I S = 5 A -0.81 1.1V Body diode reverse recovery time t rr I F = 10 A, di/dt = 100 A/μs, T J = 25 °C-126252ns Body diode reverse recovery charge Q rr -360720nC Reverse recovery fall time t a -49-nsReverse recovery rise timet b-77-TYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)On-Resistance vs. Drain Current Gate Char g e CapacitanceOn-Resistance vs. Junction TemperatureThreshold Volta g e Sin g le Pulse Power, Junction-to-AmbientSafe Operatin g Area, Junction-to-AmbientTYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)Current Deratin g aPower, Junction-to-Case Power, Junction-to-AmbientNotea.The power dissipation P D is based on T J max. = 150 °C, using junction-to-case thermal resistance, and is more useful in settling the upper dissipation limit for cases where additional heatsinking is used. It is used to determine the current rating, when this rating falls below thepackage limitTYPICAL CHARACTERISTICS (25 °C, unless otherwise noted)Normalized Thermal Transient Impedance, Junction-to-CaseVishay Siliconix maintains worldwide manufacturing cap ability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package / tape drawings, part marking, and reliability data, see /ppg?75477.。
SiliconNitride汇总
– Sintering aids(Y203)
Overview
BackgroundProcessingApplicationsTribology
Processing
– Liquid Phase Sintering – Sintering – Hot-pressing – HIP (Hot isostatic pressing) – Reaction-bonding – Sintered reaction bonding
– Strongly covalently bonded
Overview
BackgroundProcessingApplicationsTribology
Background
– Alpha and Beta Silicon Nitride – Molecular Structure – Mechanical Properties
Application of pressure during sintering is instrumental in achieving nearly full density, resulting in very good properties.
Disadvantage? High processing cost
Fracture Toughness
Addition of Y2O3 promoted the development of high aspect ratio beta Si3N4 grains
Higher aspect ratio gave a higher toughness
Processing
porosity
Evaporation of N2 (g) @ 1850 OC
晶体硅硅片、规定以及工艺过程中lifetime测试技术
7
Carrier Recombination Lifetime: 0.1 to 10,000 μs
Bulk material Cells and Passivated wafers as-cut wafers
0.01 0.1 1 10 100 1000 10000 100000
Carrier Recombination Lifetime (μ s)
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DOI: 10.1126/science.1226325, 1640 (2012);337 Science et al.Suk-Won Hwang A Physically Transient Form of Silicon ElectronicsThis copy is for your personal, non-commercial use only.clicking here.colleagues, clients, or customers by , you can order high-quality copies for your If you wish to distribute this article to othershere.following the guidelines can be obtained by Permission to republish or repurpose articles or portions of articles): September 27, 2012 (this information is current as of The following resources related to this article are available online at/content/337/6102/1640.full.html version of this article at:including high-resolution figures, can be found in the online Updated information and services, /content/suppl/2012/09/27/337.6102.1640.DC2.html/content/suppl/2012/09/26/337.6102.1640.DC1.html can be found at:Supporting Online Material /content/337/6102/1640.full.html#related found at:can be related to this article A list of selected additional articles on the Science Web sites /content/337/6102/1640.full.html#ref-list-1, 2 of which can be accessed free:cites 29 articles This article/cgi/collection/mat_sci Materials Sciencesubject collections:This article appears in the following registered trademark of AAAS.is a Science 2012 by the American Association for the Advancement of Science; all rights reserved. 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(print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the Science o n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mby a 3to 10%perturbation in the local rotation rate in the outer few percent of the Sun (16).Finally,the Sun ’s mean hexadecapole shape amplitude is small (–0.1T 0.4milli –arc sec)but shows a hint of variability (21).This value is marginally correlated with the sunspot cycle with an amplitude of 2.1T 2milli –arc sec.The hexadecapole shape is also sensitive to the in-ternal solar differential rotation,but if due only to rotation,it would require large changes (on the order of 50%)in the outer parts of the Sun (16)that are not consistent with the constant helio-seismic rotation (20)and the constant oblateness.In contrast,solar-cycle changes in near-surface flows or magnetic stresses localized near mid-latitudes could affect C 4and not the oblateness.References and Notes1.R.H.Dicke,Nature 202,432(1964).2.H.A.Hill,R.T.Stebbins,Astrophys.J.200,477(1975).3.R.H.Dicke,J.R.Kuhn,K.G.Libbrecht,Astrophys.J.318,451(1987).4.A.Egidi et al .,Sol.Phys.235,407(2006).5.J.Rösch,J.P.Rozelot,H.Deslandes,V.Desnoux,Sol.Phys.165,1(1996).6.C.Damiani,J.P.Rozelot,S.Lefebvre,A.Kilcik,A.G.Kosovichev,J.Atmos.Sol.Terr.Phys.73,241(2011).7.M.Emilio,R.Bush,J.R.Kuhn,P.Scherrer,Astrophys.J.660,L161(2007).8.M.D.Fivian,H.S.Hudson,R.P.Lin,H.J.Zahid,Science 322,560(2008).9.J.P.Rozelot,C.Damiani,Eur.Phys.J.H 36,407(2011).10.J.R.Kuhn,R.I.Bush,X.Scheick,P.Scherrer Nature 392,155(1998).11.We let L (r ,q )be the observed LDF function from a binnedsatellite image.From this,we used the circular average mean LDF represented by G (r )to solve for a brightness function a (q )and the limb shape b (q ).The binned LDF function was then expressed as L (r ,q )=[a (q )+1]G [r –b (q )],where a and b represent the mean limb brightness change and position around the limb.We then linearized this equation and solved it as a least-squares problem to find a and b .We obtained the function G (r )from the binned intensity of limb pixels,whereas we iterated the solution for b (q )so that G (r )was adjusted at each iteration by correcting the limb-pixel binning by shifting pixels by the local b (q )from the previous iteration.This was done for each of the typically 13,000images obtained during an SDO spacecraft roll.After two iterations,the solution was stable to better than 5%.12.J.Schou et al .,Sol.Phys.275,229(2012).13.Figure S1shows that the analysis recovers the limbshape,independent of any limb brightness variations.Figure S2shows that independent simultaneous HMI solar-limb shape and brightness measurements agree on all angular scales and that the limb position and brightness measurements are dominated by solar atmosphere inhomogeneity and its global asphericity.14.R.J.Bray,R.E.Loughheed,Sunspots (Wiley,New York,1965).15.Figure S3shows how the limb brightness and positionare correlated and how the brightness measurements [a ,see (11)]can be used to flag localized magnetic limb contamination of the limb shape.The shape analysis is broadly insensitive to the brightness threshold,with no significant change in the derived global oblateness,even with large changes in the assumed brightness threshold.16.J.D.Armstrong,J.R.Kuhn,Astrophys.J.525,533(1999).17.The c 2statistic for these 5degrees of freedom and aconstant to describe the Fig.4C 2data are both equal to2.8.This indicates no statistical basis for a nonconstant C 2at better than the 99.9%confidence level.18.J.R.Kuhn,M.Emilio,R.Bush,Science 324,1143(2009).19.R.I.Bush,M.Emilio,J.R.Kuhn,Astrophys.J.716,1381(2010).20.R.Howe,Living Rev.Sol.Phys.6,1(2009).21.The c 2statistic for describing the hexadecapoleamplitude as a constant was 9.4.This was marginally inconsistent (at 95%level)with a constant.Linear regression of the hexadecapole measurements against the sunspot number time series suggested a marginally significant hexadecapole solar-cycle variation with an amplitude of 2.1T 2milli –arc sec.Acknowledgments:The raw and astrometric data used for this analysis are available via the HMI public archives ().The development of the HMI astrometry pipeline was supported by NASA and a grant to Stanford Univ.and the Univ.of Hawaii (NNX09AI90G).The HMI experiment aboard the SDO satellite was funded,in part,by a NASA contract to Stanford (NAS5-02139).J.R.K.was supported by a senior Humboldt prize while some of this work was done at the Kiepenheuer Institut fur Sonnenphysik.M.E.was partially supported by Instituto Nacional de Estudos do Espaço (CNPq),CNPq grant 303873/2010-8,andCoordenação de Aperfeiçoamento de Pessoal de Nivel Superior grant 0873/11-0.We thank H.Hudson for comments on this manuscript.Supplementary Materials/cgi/content/full/science.1223231/DC1Supplementary Text Figs.S1to S3Table S1References11April 2012;accepted 7August 2012Published online 16August 2012;10.1126/science.1223231A Physically Transient Form of Silicon ElectronicsSuk-Won Hwang,1*Hu Tao,2*Dae-Hyeong Kim,3*Huanyu Cheng,4Jun-Kyul Song,5Elliott Rill,1Mark A.Brenckle,2Bruce Panilaitis,2Sang Min Won,6Yun-Soung Kim,1Young Min Song,1Ki Jun Yu,6Abid Ameen,1Rui Li,4,7Yewang Su,4Miaomiao Yang,2David L.Kaplan,2Mitchell R.Zakin,8Marvin J.Slepian,9Yonggang Huang,4Fiorenzo G.Omenetto,2,10†John A.Rogers 1,5,6†A remarkable feature of modern silicon electronics is its ability to remain physically invariant,almost indefinitely for practical purposes.Although this characteristic is a hallmark of applications of integrated circuits that exist today,there might be opportunities for systems that offer the opposite behavior,such as implantable devices that function for medically useful time frames but then completely disappear via resorption by the body.We report a set of materials,manufacturing schemes,device components,and theoretical design tools for a silicon-based complementary metal oxide semiconductor (CMOS)technology that has this type of transient behavior,together with integrated sensors,actuators,power supply systems,and wireless control strategies.An implantable transient device that acts as a programmable nonantibiotic bacteriocide provides a system-level example.An overarching goal in the development of nearly any new class of electronics is to achieve high-performance operation inphysical forms that undergo negligible change with time.Active and passive materials,device and circuit layouts,and packaging strategies are each formulated individually and then configured collectively to accomplish this outcome.Here we present concepts and strategies for electronics that involve similar attention to engineering de-signs,but with the goal of achieving systems thatphysically disappear at prescribed times and at controlled rates.Applications that could exploit this transient behavior include implantable med-ical diagnostic and therapeutic devices that resorb in the body to avoid adverse long-term effects,fieldable environmental sensors that dissolve to eliminate the need for their retrieval,and portable consumer devices that decompose to minimize the costs and health risks associated with recycling and the management of hazardous waste streams.For these three examples,the desired time scalesfor transience range from days or weeks,to months,to years,respectively.The approaches reported here can address these and other application concepts with circuit components whose opera-tional characteristics match those of nontransient counterparts formed in the usual way on silicon wafer substrates.When combined with transient sensors,actuators,power supplies,and wireless control systems,this technology provides levels of function that substantially exceed those availableREPORTS1Department of Materials Science and Engineering,Beckman Institute for Advanced Science and Technology,and Frederick Seitz Materials Research Laboratory,University of Illinois at Urbana –Champaign,Urbana,IL 61801,USA.2Department of Biomedical Engineering,Tufts University,Medford,MA 02155,USA.3School of Chemical and Biological Engineering,Center for Nanoparticle Research of Institute for Basic Science,WCU Program of Chemical Convergence for Energy and Environ-ment,Seoul National University,Seoul 151-741,Republic of Korea.4Department of Mechanical Engineering and Depart-ment of Civil and Environmental Engineering,Northwestern University,Evanston,IL 60208,USA.5Department of Chemistry,University of Illinois at Urbana –Champaign,Urbana,IL 61801,USA.6Department of Electrical and Computer Engineering,University of Illinois at Urbana –Champaign,Urbana,IL 61801,USA.7State Key Laboratory of Structural Analysis for Industrial Equipment,Department of Engineering Mechanics,Dalian University of Technology,Dalian 116024,China.8Nano Terra,Brighton,MA 02135,USA.9Department of Medicine and Department of BioMedical Engineering,Sarver Heart Center,University of Arizona,Tucson,AZ 85724,USA.10Department of Physics,Tufts University,Medford,MA 02155,USA.*These authors contributed equally to this work.†To whom correspondence should be addressed.E-mail:jrogers@ (J.A.R.);fiorenzo.omenetto@ (F.G.O.)28SEPTEMBER 2012VOL 337SCIENCE1640 o n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mFig.1.Demonstration platform for transient electronics,with key materials,device structures,and reaction mechanisms.(A )Image of a device that includes transistors,diodes,inductors,capacitors,and resistors,with interconnects and interlayer dielectrics,all on a thin silk substrate.(B )Exploded-view schematic illustration,with a top view in the lower right inset.(C )Images showing the time sequence of dissolution in DI water.(D )Chemical reactions for each of the constituent materials withwater.Fig.2.Experimental studies of transient electronic materials and devices and corresponding theoretical analysis.(A )Atomic force microscope topographical images of a Si NM (initial dimensions:3m m ×3m m ×70nm)at various stages of hydrolysis in PBS at 37°C.(B )Diagram of the processes of reactive diffusion used in models of transience.(C )Experimental (symbols)and theoretical (lines)results for time-dependent dissolution of Si NMs (35nm,black;70nm,blue;100nm,red)in PBS at 37°C.(D )Optical microscope images of the dissolution of a serpentine trace of Mg (150nm thick)on top of a layer of MgO (10nm thick)in DI water at room temperature.(E )Experimental (symbols)and theoretical (lines)results of dissolution kinetics of similar traces of Mg (300nm thick)with different encapsulating layers:MgO (400nm,red;800nm,blue)and silk (condition i,cyan;condition ii,purple).(F )Measure-ments of transience in operational characteristics of n-channel transistorsencapsulated by MgO and crystallized silk (picture in the inset on the left)and then immersed in DI water.The results show the drain current (I d )at V d =0.1V as a function of V g at various times (left)and at V g =5V as a function of time (right)SCIENCEVOL 33728SEPTEMBER 20121641REPORTSo n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mwith recently reported forms of organic electronics,in which certain constituent materials are water-soluble (1–3),or with simple nontransient tran-sistors formed on bioresorbable substrates (4).Figure 1,A and B,and fig.S1provide images and schematic diagrams of a demonstration plat-form.All of the components,ranging from the in-ductors,capacitors,resistors,diodes,transistors,interconnects,and crossovers,to the substrate and encapsulation,disintegrate and dissolve when im-mersed in deionized (DI)water (Fig.1C).This example uses magnesium (Mg)for the conduc-tors,magnesium oxide (MgO)(silicon dioxide,SiO 2,is also possible)for the dielectrics,mono-crystalline silicon (Si)nanomembranes (NMs)for the semiconductors,and silk (which is water-soluble and enzymatically degradable)(4,5)for the substrate and packaging material.The fabri-cation of systems such as this one involves a com-bination of transfer printing (Si NMs)(6),physical vapor deposition through fine-line stencil masks (Mg,MgO,and SiO 2),and solution-casting (silk).More details on sample preparation can be found in (6).As adhesion promoters for Mg,we used MgO in certain cases and ultrathin layers of Ti in others.Device yields without the Ti are 70to ~80%with evaporated Mg and >90%with sput-tered Mg.The chemical reactions responsible for the dissolution of each material appear in Fig.1D.The Si NMs and layers of SiO 2are particularly important because of their essential roles in high-performance transistors,diodes,photodetectors,solar cells,temperature sensors,strain gauges,and other semiconductor devices.The NM geom-etry is critical because it enables high-performance devices and planar architectures,minimizes the amount of material that must be consumed during the transient step,and provides mechanics and processing options that are favorable for heter-ogeneous integration onto substrates such as silk (4),as well as elastomers that can provide modulus-matched interfaces with the body (7).A typical transistor described here requires less than ~1m g of Si,which can be dissolved in as little as 30m l of biofluid (8).Figure 2A presents atomic force micrographs of a Si NM (3×3m m)with a thickness of 70nm,collected at different stages of dissolution in phosphate-buffered saline (PBS;pH of 7.4)at 37°C,to simulate transience by bioresorption (see figs.S2and S3A for additional data).The dissolution involves hydrolysis to form Si(OH)4(9),according to Si +4H 2O ↔Si(OH)4+2H 2,where SiO 2can sometimes be involved as an intermediate (10).The simplest model of thekinetics,which depends strongly on pH,consid-ers a constant reaction rate at the water/Si NM interface (11).The results capture experimental observations at both body temperature (37°C)(Fig.2C)and room temperature (25°C)(fig.S3A)for a dissolution rate of 4.5nm/day and 2nm/day,respectively,consistent with Arrhenius scaling (12).Mechanisms involving diffusion into the materials can be important for Mg and MgO deposited by electron-beam evaporation and SiO 2formed by chemical vapor deposition,or as an intermediate in the hydrolysis of Si.In such cases,the kinetics can be described analytically using models of reactive diffusion (Fig.2B)(6).The results quantitatively account for related behaviors in other materials for transient elec-tronics,including those in Fig.1(6).Figure 2D presents a meander trace of Mg (150nm)on a thin film of MgO (10nm;adhesion promoter),in which the measured changes in resistance corre-late well with those expected based on computed changes in thickness (Fig.2E and fig.S4,A and B)(6).(Other examples appear in fig.S5.)This result connects a key electrical property to models of reactive diffusion,thereby suggesting the capacity to use such analytics in conjunction with established circuit simulators as a compre-hensive design approach.REPORTSFig.3.Images and elec-trical properties of tran-sient electronic components,circuits,and sensors,in-cluding simple integrated circuits and sensor ar-rays.(A )Image of an LC (inductor-capacitor)oscil-lator fabricated with Mg electrodes and MgO di-electric layers (left)and an array of Si NM diodes with serpentine Mg re-sistors (right).(B )Mea-surements of the S21scattering parameter of an inductor (blue),capac-itor (black),and LC oscil-lator (red)at frequencies up to 3GHz (left).Current-voltage (I-V )character-istics of diodes connected to three different Mg re-sistors (right)are shown.(C )Images of an array of p-channel (left)MOSFETs and a logic gate (invert-er;right)composed of n-channel MOSFETs.The MOSFETs use Mg source (S),drain (D),and gate (G)electrodes;MgO gate dielectrics;and Si NM semiconductors.The inverter uses Mg for inter-connects and Au for source,drain,and gate electrodes,in a circuit con-figuration shown in the diagram.(D )I-V characteristics of a representative n-channel MOSFET [left,channel length (L ch )and width (W )are 20m m and 900m m,respectively].Transfer characteristic for the inverter (right,L ch and W are 20m m and 700m m for the input transistor and 500m m and 40m m for the load transistor,respectively).The voltage gain is ~8.(E )Image ofstrain sensors based on Si NM resistors (left)and an addressable array of Si NM photodetectors with blocking diodes.In both cases,Mg serves as con-tact and interconnection electrodes and MgO as the dielectric.(F )Frac-tional change in resistance of a representative strain gauge as a function of time during cyclic loading (left).R ,bent;R 0,flat.Bending induces tensile (red)and compressive (blue)strains uniaxially up to ~0.2%.Right,image of a logo collected with the photodetector array.The inset shows the logodesign.28SEPTEMBER 2012VOL 337SCIENCE1642 o n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mThe transience times for NM-based electronic components can be extended,in controlled amounts,by adding transient encapsulating layers and packaging materials;they can be reduced by decreasing the critical dimensions or by physically structuring the materials in a way that accelerates dissolution by disintegration (fig.S6).Figure 2E and fig.S4show results of measured transience in a serpentine resistor of Mg,encapsulated with different thicknesses of MgO and with combina-tions of MgO and overcoats of silk.Corresponding modeling results are also shown in (6).Silk is attractive for this purpose because its solubility in water can be programmed,over several orders of magnitude,through the control of crystallinity (5,13).Other biodegradable polymers can also be used,as shown in fig.S7.Studies of transience at the device level are also important.Figure 2F shows examples of metal oxide semiconductor field-effect transis-tors (MOSFETs)formed using Si NMs,SiO 2gate dielectrics,and Mg electrodes,with encapsulating layers of MgO and crystallized silk.The devicesshow two-stage kinetics in their functional tran-sience.Immersion in DI water for up to ~90hours causes negligible change in key device charac-teristics.Functional degradation then occurs in a relatively narrow time interval after this period of stable operation.The encapsulation defines the first time scale;the Mg electrodes define the second.The results demonstrate that the tran-sience time can be engineered in a way that is decoupled from system-or device-level function.These materials,fabrication techniques,and modeling tools can yield components for almost any type of transient electronic system,in CMOS designs.Figure 3presents several examples,in-cluding additional details on MOSFETs similar to those in Fig.2F,where both n-and p-channel operation is possible.The resulting electrical prop-erties for an n-channel device include satura-tion and linear regime mobilities of 560cm 2/V·s and 660cm 2/V·s,respectively,on/off ratios of >105,subthreshold slopes of 160mV/dec [at drain voltage (V d )=0.1V]and width-normalized current outputs of 0.34mA/mm [at gate voltage(V g )=5V].These characteristics,as well as those of similar p-channel devices,compare favor-ably to the performance of counterparts formed on Si-on-insulator (SOI)wafers (14).[For the range of channel lengths investigated,contact resistances do not limit performance (fig.S8).]In all cases,the transience times of different elements in an in-tegrated system can be controlled by use of varied thicknesses and/or stack compositions,or even via combination with nontransient materials.This last possibility is shown in a logic gate (inverter)in the righthand panels of Fig.3,C and D,where a non-transient metal (Au)serves as source,drain,and gate electrodes for two transistors joined by tran-sient Mg interconnects.Many other classes of semiconductor devices and passive components are possible,with exam-ples in Fig.3and figs.S9and S10.The resistors and diodes can serve as temperature sensors;the latter can also be used in photodetectors and solar cells,as shown in Fig.3and fig.S10.The Si NM diode and Mg resistive temperature sen-sors show sensitivities of –2.23mV/°C (change inFig.4.In vivo evaluations and example of a transient bioresorbable device for thermal therapy.(A )Images of an implanted (left)and sutured (right)demonstra-tion platform for transient electronics located in the subdermal dorsal region of a BALB/c mouse.(B )Implant site after 3weeks (left).(Right)Histological section of tissue at the implant site,excised after 3weeks,showing a partially resorbed region of the silk film.(A,subcutaneous tissue;B,silk film;C,muscle layer).(C )Resonant responses of an implanted transient rf meta-material structure before and after placement in a silk package,immediately after implantation and at several time intervals there-after.(D )Measured and calculated Q factor for the metamaterial.The results in-dicate transience dominated by the diffusion of biofluids through the silk package.(E )Transient wireless device for thermal therapy,consisting of two resistors (red outline)connected to a first wireless coil (70MHz;outer coil)and a second resistor (blue out-line)connected to a second,independently addressable,wireless coil (140MHz;inner coil).The inset shows a thermal image of this device coupled with a primary coil operating at two frequencies,to drive both the inner and outer coils simultaneously.(F )Primary coil next to a sutured implant site for a transient thermal therapydevice.The inset shows an image of a device.(G )Thermal image collected while wirelessly powering the device through the skin;the results show a hot spot (5°C above background)at the expected location,with a magnified view in theSCIENCEVOL 33728SEPTEMBER 20121643REPORTSo n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o mvoltage for a given current output)and 0.23%/°C (percentage change in resistance),both of which are consistent with the behavior of conventional,nontransient devices (15).Ultrathin Si solar cells (~3m m thick)provide fill factors of 66%and overall power conversion efficiencies of ~3%,even without light-trapping structures,backside reflectors,or antireflection coatings.Doped Si NMs can serve as strain gauges (Fig.3E,left),with gauge factors of nearly ~40(Fig.3F,left,and fig.S10B),which are comparable to those of state-of-the art devices (16).As an example of interconnected components,we built a tran-sient digital imaging system,consisting of col-lections of Si NM photodiodes with blocking diodes for passive matrix addressing (Fig.3E,right),capable of capturing pictures when op-erated in a scanned mode (Fig.3F,right,and fig.S10D).(See more details on device dimen-sions in fig.S11.)The yield here is >90%[i.e.,58out of 64pixels were fully functional (fig.S12)].One possibility for power supply involves Si solar cells such as those shown in fig.S10A.Another uses inductors and capacitors like those in Figs.1A and 3A and fig.S9as wireless an-tennas for near-field mutual inductance coupling to separately powered,external primary coils.This option is interesting for implantable devices (4),made possible by the biocompatibility of the constituent materials (Fig.1),as established in unrelated contexts (6).To demonstrate opportunities,we conducted a series of in vivo and in vitro experiments.V ar-ious representative transient devices were fab-ricated,sealed in silk packages,sterilized with ethylene oxide,and then implanted in the sub-dermal region of BALB/c mice in accordance with Institutional Animal Care and Use Commit-tee protocols.Figure 4A shows the case of the platform in Fig.1.Examination after 3weeks (Fig.4B,left)revealed only faint residues,with evidence of slow reintegration into the subdermal layers,along with apparent revascularization.The histological section in Fig.4B (right)shows the subdermal layer (A),the silk film (B),and the mus-cle layer (C)and reveals no significant inflamma-tory reactions.Additional analysis appears in fig.S13.Inductive coils of Mg combined with resistive microheaters of doped Si NMs,integrated on silk substrates and housed in silk packages,can pro-vide transient thermal therapy to control surgi-cal site infections (17,18)as a nonantibiotic,programmable bacteriocidal appliquéthat dis-appears as the patient moves beyond the period of greatest risk.In vitro tests demonstrate the efficacy of this approach (6).Figure 4,C and D,present a metamaterial rf antenna,as a gen-eralized component for such a device,capable of continuous wireless monitoring after implan-tation.The data indicate transient behavior asso-ciated with the slow diffusion of biofluids through the edges of the silk package,with a measured quality (Q )factor that has time dependence consistent with theoretical models (6).Figure 4E shows an image of a functional device formedon glass that includes two coils with different resonance frequencies (~70and ~140MHz)and three separate heaters.Wirelessly operating either or both of these coils with appropriate frequen-cies and power levels applied to a separate pri-mary coil enables full control of the system,as illustrated in the thermal image in the inset.(See figs.S14to S16for other examples.)To illustrate in vivo functionality,a fully transient version of this device was implanted under the skin of a Sprague-Dawley rat (Fig.4F).Inductive coupling through the skin generates a localized temper-ature increase of D T ~5°C (Fig.4G),coincident with the position of the heater.The functional transience has a time scale of 15days,chosen via the crystallinity of the silk,to coincide with the most critical period,which is the first few days after an operation,to sterilize and maintain asepsis at the wound site.After this time,the device dis-appears,leaving only remnants of silk,which resorb on longer time scales,to eliminate the long-term burden associated with additional exoge-nous implant material.Concepts reported here establish a baseline of materials,modeling approaches,manufacturing schemes,and device designs for transient elec-tronic systems,sensors,actuators,and power sup-plies.The Si NMs are critically important elements,because their use enables sophisticated semi-conductor components with both active and passive functionality.For the dielectrics and conductors,additional possibilities range from collagen to poly(lactic-co-glycolic acid)and from iron to zinc,respectively.Alternative modes of transience in-clude absorption,corrosion,and depolymerization.The rates for these processes could,conceivably,be adjustable in real time and/or sensitive to the properties of the surrounding environment,deter-mined by chemical or biological events,or changes in temperature,pressure,or bining such possibilities in transience with ideas in soft,tissue-like electronics will further expand opportunities for applications in biomedical devices (7).References and 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24,380(1996).18.D.J.Anderson et al .,PLoS ONE 4,1(2009);/10.1371/journal.pone.0008305.Acknowledgments:The work on materials,integrationschemes,manufacturing approaches,and design strategies was supported by the Defense Advanced Research Projects Agency.The theoretical analysis and associated experiments were supported by an NSF INSPIRE grant.The techniques forcreating and manipulating Si nanomembranes were developed in work supported by an Air Force Office of Scientific Research Multi University Research Initiative program.The animalstudies were funded by the National Institutes of Health (grant EB002520).The facilities for characterization and analysis were provided by the Material Research Laboratory and Center for Microanalysis of Materials at the University of Illinois at Urbana –Champaign,both of which are supported by the U.S.Department of Energy.Supplementary Materials/cgi/content/full/337/6102/1640/DC1Materials and Methods Figs.S1to S22References (19–32)19June 2012;accepted 29August 201210.1126/science.1226325Gold-Catalyzed Direct ArylationLiam T.Ball,Guy C.Lloyd-Jones,*Christopher A.Russell *Biaryls (two directly connected aromatic rings,Ar 1-Ar 2)are common motifs in pharmaceuticals,agrochemicals,and organic materials.Current methods for establishing the Ar 1-Ar 2bond are dominated by the cross-coupling of aryl halides (Ar 1-X)with aryl metallics (Ar 2-M).We report that,in the presence of 1to 2mole percent of a gold catalyst and a mild oxidant,a wide range of arenes (Ar 1-H)undergo site-selective arylation by arylsilanes (Ar 2-SiMe 3)to generate biaryls (Ar 1-Ar 2),with little or no homocoupling (Ar 1-Ar 1/Ar 2-Ar 2).Catalysis proceeds at room temperature and tolerates a broad range of functional groups,including those incompatible with cross-coupling.These features expedite biaryl preparation,as demonstrated by synthesis of the nonsteroidal anti-inflammatory diflunisal.The biaryl moiety (two directly connected aromatic rings,Ar 1-Ar 2)is a common functionality in pharmaceuticals [such as Lipitor,Crestor,and Diovan,three of themost widely prescribed drugs in 2010(1)];in agrochemicals;and in many modern organic ma-terials,including liquid crystal displays,light-emitting diodes,and conducting polymers.TheREPORTS28SEPTEMBER 2012VOL 337SCIENCE1644 o n S e p t e m b e r 27, 2012w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o m。