OLED外文文献翻译
LED点阵显示屏中英文对照外文翻译文献
LED点阵显示屏中英文对照外文翻译文献(文档含英文原文和中文翻译)译文:基于AT89C52单片机的LED显示屏控制系统的设计摘要这篇文章介绍了基于AT89C52单片机的LED点阵显示屏的软件和硬件开发过程。
使用一个简单的外部电路来控制像素是32×192的显示屏。
用动态扫描,显示屏可以显示6个32×32的点阵汉字。
显示屏也可以分为两个小的显示屏,它可以显示24个像素是16×16的汉字。
可以通过修改代码来改变显示的内容和字符的滚动功能,而且可以根据需要调整字符的滚速或者暂停滚动。
中文字符代码存储在外部存储寄存器中,内存的大小由需要显示的汉字个数决定。
这种显示屏具有体积小,硬件和电路结构简单的优点。
关键词发光二极管汉字显示AT89C52单片机1.导言随着LED显示屏不断改善和美化人们的生活环境,LED显示屏已经成为城市明亮化,现代化、信息化的一项重要标志。
在大的购物商场,火车站,码头,地铁,大量的管理窗口等,我们经常可以看到LED灯光。
LED商业已成为一个快速增长的新产业,拥有巨大的市场空间和光明前景。
文章,图片,动画和视频通过LED发光显示,并且内容可以变换。
一些显示设备的模块化结构,通常有显示模块,控制系统和电源系统。
显示模块是由LED管组成的点阵结构,进行发光显示,可以显示文章,图片,视频等。
控制系统可以控制区域里LED的亮灭,电源系统为显示屏提供电压和电流。
用电脑,取出字符字节,传送到微控制器,然后送到LED点阵显示屏上进行显示,很多室内和室外显示屏都是通过这个方法进行显示的。
按显示的内容区分,LED点阵屏的显示可分为图形显示、图片显示和视频显示三个部分。
与图片显示屏比较,不管是单色或者彩色的图形显示屏,都没有灰色色差,所以,图形显示不能反映丰富的色彩。
视频显示屏不但可以显示运动、清楚和全彩的图像,也可以显示电视和计算机信号。
虽然三者之间有一些不同,但显示的原理基本一样。
专业英语 缩写翻译
ABI 应用二进制接口(Application Binary Interface)ACSI 国家信息化咨询委员会(advisory committee for state informatization)ADSL 非对称数字用户线路(Asymmetric Digital Subscriber Line)AI 人工智能(artificial intelligence)AMPS 高级移动电话系统(Advanced Mobile Phone System)API 应用程序接口(Application Programming Interface)ASIC 特定用途集成电路(Application Specific Integrated Circuit)ASTM 美国试验材料学会(American Society for Testing Material)AT&T 美国电话电报公司(American Telephone and Telegraph Company)ATM 异步传输模式(Asynchronous Transfer Mode)ATOS Origin 源讯公司Auto-ID 自动识别(Auto-ID)AWS 美国航空气象处(Air Weather Service);BAP 基本汇编程序(Basic Assembler Program)BGA 集成电路采用有机载板的一种封装法BOINC 伯克利开放式网络计算 (Berkeley Open Infrastructure For Network Computing ) BSP 板级支持包(Board Support Package)Business Processing 业务处理流程CaaS 通信即服务(communication as a Service)CAN 控制器局域网络(Controller Area Network)CAS 中国科学院(Chinese Academy of SciencesCCTV 中国中央电视台(China Central Television)CDMA2000 电信移动通信系统CIP 预编目录(cataloging in publication)CITYNET 城市间合作网络CMU 卡内基梅隆大学(Carnegie Mellon University)CN 通信网络(Communicating Net)CPU 中央处理机(Central Processing Unit)CRA 应答验证 (challenge-response authentication)DARPA 美国国防部高级研究计划局(Defense Advanced Research Projects Agency)DARPA 研究计划署(Defense Advanced Research Projects Agency)DASH7Data mining 数据挖掘技术(即指从资料中发掘资讯或知识)DDoS 分布式拒绝服务(Distributed Denial of Service)DG INFSO 媒体总司DG INFSO/D4 欧盟委员会DGINFSO‐D4DMM 分布式内存多处理器(distributed memory multiprocessor)DNS 域名服务器(Domain Name Server)DoD 美国国防部(Department of Defense of the United States)DRAM 动态随机存取存储器(Dynamic Random Access Memory)DSL 数字用户线路(Digital Subscriber Line)DSP 数字信号处理器(Digital Signal Processor)DSS 决策支持系统(Decision Support Systems)DynDNS 动态DNSEAN 欧洲商品编码(Europ Article Number)EAS 电子防窃系统(Electronic Article Surveillance)ECMA 欧洲电脑制造商协会(European Computer Manufactures Association)EPC 电子产品代码(Electronic Product Code)EPCglobal 国际物品编码协会EAN和美国统一代码委员会( UCC )的一个合资公司ERP 企业资源计划(Enterprise Resource Planning)ETSI 欧洲电信标准协会(European Telecommunication Standards Institute)EU-funded CASAGRAS1 coordination 欧盟资助CASAGRAS1协调FAT 文件分配表(File Allocation Table)FP7 欧盟第七框架计划(Framework Program 7)FreeOTFE 免费实时加密FSTC 金融服务技术联盟(Financial Services Technology Consortium)FTP 文件传输协议(File Transfer Protocol)GM 通用汽车公司(General Motors)GMSA 全球移动通信系统协会(global system for mobile communications association) GPRS 通用分组无线业务(General Packet Radio Service)GPS 全球定位系统(Global Position System)GSM 全球移动通信系统(Global System for Mobile Communications)GUI-based 图形用户界面HP 惠普公司HTML5 HTML5是HTML下一个的主要修订版本,现在仍处于发展阶段HTTP 超文本传输协议(Hyper Text Transport Protocol)HTTPS 安全超文本传输协议(Hypertext Transfer Protocol Secure)I²C 两线式串行总线(Inter-Integrated Circuit)IaaS 架构即服务(Infrastructure As A Service)IATA 国际航空运输协会(International Air Transport Association)ICC 集成电路卡(integrated circuit card)ICT 集成电路计算机遥测技术(Integrated Computer Telemetry)iDA 资讯通信发展管理局(infocomm Development Authority)IEC 国际电工技术委员会(International Electrotechnical Commission)IEEE 电气与电子工程师协会(Institute of Electrical and Electronic Engineers)IETF Internet工程任务组(Internet Engineering Task Force)IMT-2000 国际移动电话系统-2000(International Mobile Telecom System-2000)IOT 物联网(Internet Of Things)IPSec 网际协议安全(Internet Protocol Security)IPSO 因特网协议安全选件(Internet protocol security option )IPv4 IPv4,是互联网协议(Internet Protocol,IP)的第四版IR 指令寄存器(instruction register)ISA 工业标准总线(Industry Standard Architecture)ISM 美国供应管理协会(the Institute for Supply Management , ISM)ISO 国际标准化组织(International Standardization Organization)ISTAG IST咨询集团(IST advisory group)IT 信息技术(Information Technology)ITSO_LtdITU 国际电信联盟(International Telecommunication Union)KAEC 阿卜杜拉国王经济城(King Abdullah Economic City)KVM 基于内核的虚拟机(K Virtual Machine)LAN 局域网(local area network)LCD 液晶显示屏(liquid crystal display)LR-WPAN 低速率无线个人区域网络(Low Rate-Wireless Personal Area Network)LSI 大规模集成电路(Large Scale Integrated circuit)MAC 多路存取计算机(Multi-Access Computer)MAN 城域网(Metropolitan Area Network)MASDAR 马斯达尔MEMS 微电子机械系统(Micro-electromechanical Systems)METI 日本经济贸易产业省(Ministry of Economy, Trade and Industry)MIC 部门内部事务和通讯(the ministry of internal affairs and communications) MIT 麻省理工学院(Massachu-setts Institute of Technology);MPP 大量信息并行处理机,大规模并行处理机(Massively Parallel Processor)MRI 核磁共振成像(Magnatic Resonance Imaging);MSI 中规模集成电路(medium-scale integration)MVNO AdicaNaaS 网络即服务(Network As A Service)NASA 美国国家航空和宇宙航行局(National Aeronautics and Space Administration)NetBSD 一个免费的,具有高度移植性的UNIX-like操作系统NFC 近场通讯(Near Field Communication)NFCIPNIC 网络接口卡(Network Interface Card)NMT 北欧移动电话(Nordic Mobile Telephone)NSF (美国)国家科学基金会(National Science Foundation)NTT DoCoMo 移动通信网公司NYU 纽约大学(New York University)OLED 有机发光二极管(Organic Light Emitting Diode)ONS 国家统计局(Office For National Statistics)P2P 点对点技术(peer-to-peer);PaaS 平台即服务(Platform As A Service)PARC 帕洛阿尔托研究中心(Palo Alto Research Center)PC 个人电脑(Personal Computer);PCI 外部控制器接口(Peripheral Component Interconnect)PHY 物理层协议(Physical Layer)PKI 公钥基础设施(Public Key Infrastructure)POTS 普通老式电话服务(Plain Old Telephone Service)QNX 嵌入式实时操作系统(Quick Unix )R&D 研发(Research & Development)RACO 德国雷科resPONDER 响应器RFID 无线射频识别(radio frequency identification devices)RISC 精简指令集计算机(Reduced Instruction-Set Computer)ROM 只读存储器(read only memory)RS-232 串行数据通信的接口标准RTOS 实时操作系统(Real Time Operating System)SaaS 软件即服务(Software as a Service)SAP SAP是目前全世界排名第一的ERP软件SAVVIS 维斯公司SCADA 监测控制和数据采集(supervisory control and data acquisition)SIM 用户身份识别卡(subscriber identity module)SIMD 单指令多数据(Single Instruction Multiple Data)SIMIT 中国科学院上海微系统与信息技术研究所SMP 对称多处理机(SymmetricalMulti-Processing)SOC 片上系统(System on a Chip)SPOM 自动程序单芯片微处理(Self Programmable One Chip Microprocessor)SPT 季票 (season parking ticket)SRI 斯坦福研究院(Stanford Research Institute)SSE 单指令多数据流式扩展 ( streaming SIMD extensions)SSI 小规模集成(电路)(Small Scale Integration);SSO 单点登录(single sign-on)T2TITTACS 全接入通信系统(Total Access Communication System)TCB 可信计算基(Trusted Computing Base)TCP/IP 传输控制/网络通讯协定(Transmission Control Protocol / Internet Protocol)TD-SCDMA 即时分同步的码分多址技术(Time Division-Synchronization Code Division Multiple Access)TEDS 传感器电子数据表(Transducer Electronic Data Sheet)TLS/SSL SSL(Secure Sockets Layer,安全套接层)TPANSmitterTRON 实时操作系统核心程序(The Realtime Operating System Nucleus)U.S.Department of Defence 美国国防部UCC 统一编码委员会(uniform code council inc)UCLA 加州大学洛杉矶分校(University of California at Los Angeles)UHF 超高频(Ultra High Frequency)UML 统一建模语言(Unified Modeling Language)UNL 无处不在的网络实验室(ubiquitous networking laboratory)USAID 美国国际开发署(United States Agency for International Development)USB 通用串行总线(Universal Serial Bus)USDA 美国农业部(United States Department of Agriculture)VLSI 超大规模积体电路(Very Large Scale Integrated Circuites)VNP-VNOWAN 广域网(Wide Area Network)WCDMA 宽带码分多址移动通信系统(Wideband Code Division Multiple Access)Wi-Fi 无线上网技术WROM 一次写/读很多内存(write once/read many memory)WSN 无线传感网络(wireless sensor network)。
关于LED的外文文献和中文译文
多个LED发光装置的新型采集系统作为光源的一种,发光二极管(LED)有很多优点。
LED集成度更高,颜色种类多,使用寿命更长,而且工作电压较低。
但是,它仍有一个非常大的缺陷:一只LED的光照强度还是比较低。
这个缺点导致显示屏上的光通量不会很高。
但是无论如何,LED还是以其出色的性能在低电压装置中普遍应用。
因此,利用此系统采集多个LED的光,集成为更高强度的照明装置。
本设计提出三种采集系统,来实现增强光强的功能。
效率最好的一种采集系统可以达到96%。
同时,还分析了本系统的制造误差以及预算。
1 简介利用传统的光源来设计一个便携式探照灯,尺寸和能耗会很大。
而利用LED 来设计将会避免这些问题。
LED有很多优点:节能、体积较小、使用寿命长(约100,103小时)等,尤其是LED的光很适合环境工作。
Carel Zeiss和Philips打算用LED光源设计两种便携式探照灯。
尽管LED有诸多优点,可以让他们设计出的探照灯更加便携和小巧,但是由于光学元件的转换效率问题,导致系统有很多困难。
解决这个困难将是本文研究的重点。
通常,用一种合成非线性集中器(CPC)来减小分散度。
但是,这种传统的CPC采集效率仅为72%,必须要改善采集效率来提高光的利用率。
本文中将解决分散度和采集效率两个问题。
为实现这个目标,设计了三种不同的采集系统,以提高效率,下面逐一介绍。
2 仿真部分利用光学仿真软件和标签查找模块(BRO),来设计并分析采集系统的性能。
LED光源部分来自Osram-Opical半导体。
远程LED光源是一种Lambertian模式,LED的规格见表1。
在采集系统的底部有四个LED。
系统各个LED之间的位置关系如图1。
通光部分为2.1×2.1mm2,孔径3.26mm。
LED阵列对称的分布于系统的底部。
采集系统的第一个光学元件为均质器。
这个均质器的受光角度是12.5°。
因此,这个系统就是要把LED的受光角度的范围控制在±60°到±12.5°之间。
LED和OLED区别
,AMOLED主要有如下几个优势:1,超轻薄简单结构:由于工作原理不同,AMOLED屏幕可以做到更轻更薄,更适合对体积要求严格的便携设备。
2,超宽可视角度:AMOLED屏幕上下左右的可视角度均超过178度,相当于普通TFT 屏幕90度可视范围的两倍。
使用者眼睛也不易疲劳的同时,宽广的可视角度也方便多人观看,分享美妙视频乐趣。
3,超高响应速度:采用AMOLED的屏幕可以将响应时间缩减至小于0.01ms,相当于普通TFT屏幕的3000倍,有助于提升高速视频画面的流畅感与清晰度。
4,超高对比度:AMOLED面板的对比度高达10000:1,而普通TFT屏幕的对比度只有200:1,前者是后者的50倍,因此色彩显示更加鲜明,用户直观感受更加理想。
5,超广色域:AMOLED面板具有超广色域,接近100%色彩还原显示,其色彩显示色域达到了NTSC的114%,大大超过了普通TFT的68%,色彩表现更加饱和逼真。
6,超节能设计:AMOLED屏幕相对于普通TFT屏幕,其耗电量还不到同尺寸TFT 屏幕的60%,可大大延长电子设备的续航时间。
液晶屏lcd和led的区别LED是发光二极管Light Emitting Diode的英文缩写。
LED应用可分为两大类:一是LED单管应用,包括背光源LED,红外线LED等;另外就是LED显示屏,目前,中国在LED基础材料制造方面与国际还存在着一定的差距,但就L ED显示屏而言,中国的设计和生产技术水平基本与国际同步。
LED显示屏是由发光二极管排列组成的一显示器件。
它采用低电压扫描驱动,具有:耗电少、使用寿命长、成本低、亮度高、故障少、视角大、可视距离远等特点。
LCD显示器的原文是Liquid Crystal Display,取每字的第一个字母组成,中文多称「液晶平面显示器」或「液晶显示器」。
其工作原理就是利用液晶的物理特性:通电时排列变得有序,使光线容易通过;不通电时排列混乱,阻止光线通过,说简单点就是让液晶如闸门般地阻隔或让光线穿透。
光学外文文献及翻译
学号2013211033 昆明理工大学专业英语专业光学姓名辜苏导师李重光教授分数导师签字日期2015年5月6日研究生部专业英语考核In digital holography, the recording CCD is placed on the ξ-ηplane in order to register the hologramx ',y 'when the object lies inthe x-y plane. Forthe reconstruction ofthe information ofthe object wave,phase-shifting digital holography includes two steps:(1) getting objectwave on hologram plane, and (2) reconstructing original object wave.2.1 Getting information of object wave on hologram plateDoing phase shifting N-1 times and capturing N holograms. Supposing the interferogram after k- 1 times phase-shifting is]),(cos[),(),(),,(k k b a I δηξφηξηξδηξ-⋅+= (1) Phase detection can apply two kinds of algorithms:synchronous phase detection algorithms [9]and the least squares iterative algorithm [10]. The four-step algorithm in synchronous phase detection algorithm is in common use. The calculation equation is)2/3,,(),,()]2/,,()0,,([2/1),(πηξπηξπηξηξηξiI I iI I E --+=2.2 Reconstructing original object wave by reverse-transform algorithmObject wave from the original object spreads front.The processing has exact and clear description and expression in physics and mathematics. By phase-shifting technique, we have obtained information of the object wave spreading to a certain distance from the original object. Therefore, in order to get the information of the object wave at its initial spreading position, what we need to do is a reverse work.Fig.1 Geometric coordinate of digital holographyexact registering distance.The focusing functions normally applied can be divided into four types: gray and gradient function, frequency-domain function, informatics function and statistics function. Gray evaluation function is easy to calculate and also robust. It can satisfy the demand of common focusing precision. We apply the intensity sum of reconstruction image as the evaluation function:min ),(11==∑∑==M k Nl l k SThe calculation is described in Fig.2. The position occurring the turning point correspondes to the best registration distanced, also equals to the reconstructing distance d '.It should be indicated that if we only need to reconstruct the phase map of the object wave, the registration distance substituted into the calculation equation is permitted having a departure from its true value.4 Spatial resolution of digital holography4.1 Affecting factors of the spatial resolution of digital holographyIt should be considered in three respects: (1) sizes of the object and the registering material, and the direction of the reference beam, (2) resolution of the registering material, and (3) diffraction limitation.For pointx2on the object shown in Fig.3, the limits of spatial frequency are λξθλθθ⎥⎦⎤⎢⎣⎡⎪⎪⎭⎫ ⎝⎛-'-=-=-0211maxmax tan sin sin sin sin z x f R R Fig.2 Determining reconstructing distanceλξθλθθ⎥⎦⎤⎢⎣⎡⎪⎪⎭⎫⎝⎛-'-=-=-211minmintansinsinsinsin zxfRRFrequency range isλξξ⎥⎦⎤⎢⎣⎡⎪⎪⎭⎫⎝⎛-'-⎥⎦⎤⎢⎣⎡⎪⎪⎭⎫⎝⎛-=∆--211211tansintansinzxzxfso the range is unrelated to the reference beam.Considering the resolution of registering material in order to satisfy the sampling theory, phase difference between adjacent points on the recording plate should be less than π, namely resolution of the registration material.cfff=∆η21)(minmax4.2 Expanding the spatial resolution of reconstruction imageExpanding the spatial resolution can be realized at least in three ways: (1) Reducing the registration distance z0 can improve the reconstruction resolution, but it goes with reduction of the reconstruction area at the same ratio.Therefore, this method has its limitation. (2) Increasing the resolution and the imaging size of CCD with expensive price. (3) Applying image-synthesizing technique[11]CCD captures a few of images between which there is small displacement (usually a fraction of the pixel size) vertical to the CCD plane, shown in Fig.4(Schematic of vertical moving is the same).This method has two disadvantages. First, it is unsuitable for dynamic testing and can only be applied in the static image reconstruction. Second, because the pixel size is small (usually 5μm to 10μm) and the displacement should a fraction of this size (for example 2μm), it needs a moving table with high resolution and precision. Also it needs high stability in whole testing.In general, improvement of the spatial resolution of digital reconstruction is Fig.3 Relationship between object and CCDstill a big problem for the application of digital holography.5 Testing resultsFig.5 is the photo of the testing system. The paper does testing on two coins. The pixel size of the CCD is 4.65μm and there are 1 392×1 040 pixels. The firstis one Yuan coin of RMB (525 mm) used for image reconstruction by phase-shifting digital holography. The second is one Jiao coin of RMB (520 mm) for the testing of deformation measurement also by phase-shifting digital holography.5.1 Result of image reconstructionThe dimension of the one Yuancoin is 25 mm. The registrationdistance measured by ruler isabout 385mm. We capture ourphase-shifting holograms andreconstruct the image byphase-shifting digital holography.Fig.6 is the reconstructed image.Fig.7 is the curve of the auto-focusFig.4 Image capturing by moving CCD along horizontal directionFig.5 Photo of the testing systemfunction, from which we determine the real registration distance 370 mm. We can also change the controlling precision, for example 5mm, 0.1 mm,etc., to get more course or precision reconstruction position.5.2 Deformation measurementIn digital holography, the method of measuring deformation measurement differs from the traditional holography. It gets object wave before and after deformation and then subtract their phases to obtain the deformation. The study tested effect of heating deformation on the coin of one Jiao. The results are shown in Fig.8, Where (a) is the interferential signal of the object waves before and after deformation, and (b) is the wrapped phase difference.5.3 Improving the spatial resolutionFor the tested coin, we applied four sub-low-resolution holograms to reconstruct the high-resolution by the image-synthesizing technique. Fig.9 (a) is the reconstructed image by one low-resolution hologram, and (b) is the high-resolution image reconstructed from four low-resolution holograms.Fig.6 Reconstructed image Fig.7 Auto-focus functionFig.8 Heating deformation resultsFig.9 Comparing between the low and high resolution reconstructed image6 SummaryDigital holography can obtain phase and amplitude of the object wave at the same time. Compared to other techniques is a big advantage. Phase-shifting digital holography can realize image reconstruction and deformation with less noise. But it is unsuitable for dynamic testing. Applying the intensity sum of the reconstruction image as the auto-focusing function to evaluate the registering distance is easy, and computation is fast. Its precision is also sufficient. The image-synthesizing technique can improve spatial resolution of digital holography, but its static characteristic reduces its practicability. The limited dimension and too big pixel size are still the main obstacles for widely application of digital holography.外文文献译文:标题:图像重建中的相移数字全息摘要:相移数字全息术被用来研究研究艺术品的内部缺陷。
LED点阵的外文翻译---纳米结构InGaN发光Diodesfor固态照明
(要求翻译与毕业设计(论文)相关的外文文献两篇,且3000单词以上/ 篇,将译文附在原文之后)第一篇:[ 所译外文资料:①作者:Taeil Jung②书名(或论文题目):Nano-structured InGaN Light-Emitting Diodesfor Solid-State Lighting③出版社(或刊物名称或可获得地址):All Rights Reserved.④出版时间(或卷期号):2009.⑤所译起止页码:Nano-structured InGaN Light-Emitting Diodesfor Solid-State LightingSolid-state lighting can potentially reduce the electricity consumption by 25%. It requires high efficiency light-emitting diodes across the visible spectrum. GaN and related materials have direct band gap across the entire visible spectrum and are ideal for future solid-state lighting applications. However, materials defects, polarization charges, and total internal reflection have thus far limited the efficiencies of InGaN LEDs, in particular InGaN LEDs in the green/yellow wavelength range, which are critical in achieving highly efficient LED luminaries with an excellent color-rendering indexIn this Thesis, we have developed and demonstrated that novel in situ nanostructured GaN processes in MOCVD are effective in improving the efficiencies of InGaN LEDs. InGaN LEDs grown on quasi-planar semi-polar GaN templates were proven to exhibit three times higher internal quantum efficiencies and negligible quantum confined Stark effect using selective area epitaxy. InGaN LEDs grown on nanostructured semi-polar GaN templates are also effective to improve the internal quantum efficiency by 31%. The same in situ processes are also effective in reducing the defect density by an order of magnitude and increasing the photon extraction efficiency as a factor of two.The in situ processes include in situ silane treatment and high temperature overgrowth. Both processes require only standard MOCVD tools and hence are cost effective and suitable for mass-production. In situ silane treatment treatsc-plane GaN samples with silane under ammonia environment, generating nano-scale truncated cone structures with up to 200 nm scale. These truncated cone structures can be subsequently transformed into pyramidal nanostructures comprising of only (10-11) and (11-22) semipolar planes using high temperature overgrowth. These processes were applied to both InGaN active region and the LED surface to improve the internal quantum efficiency and the photon extraction efficiency, respectively. Extensive materials, device, and optical characterizations have been carried out in this research.1.1 Gallium Nitride Materials for Optoelectronic ApplicationsGallium nitride based materials, including GaN, AlN, InN, and their alloys, are excellent candidates for short-wavelength optoelectronic applications. Their direct bandgaps extend from ultraviolet to near-infrared. In addition, they exhibit high mechanical and thermal stabilities compared to other III-Vsemi-conductors, making them especially suitable for high-power andhigh-temperature operations. In recent years, breakthroughs in p-type doping and defect reduction have led to the commercialization of GaN based laser diodes, light-emitting diodes (LEDs), high electron mobility transistors (HEMT) and hydrogen detectors. Despite these advances, many technological challenges such as green gap and substrate growths still remain.Perhaps one of the most important applications for GaN based materials is solidstate lighting (SSL). Worldwide, lighting constitutes 20% of electricity consumption while its efficiency is much lower than 25%. In contrast, efficiency of space heating has exceeded 90%. To this end, the development of highly efficient and reliable LEDs for solid-state lighting has been very active in both industry and academia in the past few years. It is projected by the US Department of Energy that by 2015, if successful, solidstate lighting can reduce the overall electricity consumption by 25%.Unlike GaAs and InP based semi-conductors, GaN based materials have suffered from a high density of defects due to very limited availability of lattice-matched GaN substrates. Up to now, most GaN based optoelectronic devices have been fabricated using hetero-epitaxy on foreign substrates such as sapphire (Al2O3), silicon carbide (SiC), and aluminum nitride (AlN), and in a very small percentage on silicon. Because of large lattice mismatch, GaN grown on these substrates often exhibits a high density of threading dislocations, typically on the order of 108 – 1010 /cm2. These defects are still one of the major limiting factors for the performance of GaN based optoelectronic devices, acting as non-radiative recombination and scattering centers. Achievement of lower defect density would also improve device reliability, resulting in a longer lifetime. Various defect reduction approaches, such as epitaxial lateral over-growth (ELOG), have been demonstrated and some of the details will be discussed in Chap.1.3.1. As part of this thesis, we have explored a novel approach to using nano-structured GaN to effectively lower the threading dislocation density.Among various epitaxial techniques that have been developed for GaN based materials, metal-organic chemical vapor deposition (MOCVD) is the leading technology. The typical growth temperature for GaN materials is around 1000 to 1200°C. This high growth temperature is necessary to improve the crystal quality and is a result of low cracking efficiency of the nitrogen source, ammonia (NH3), at a low temperature. In Chapter 2, I will summarize my contributions to successfully ramp up an MOCVD tool for the epitaxial growth of GaN LEDs for this research.1.2 InGaN LEDs for Solid-State LightingThe basic component for SSL is a white-light LED. As shown in Figure 1-1, itcan be achieved by mixing various color components, which can be generated either from the direct output of individual LEDs or from color-conversion materials, such as phosphor. To date, commercially available white-light LEDs usually consist of a blue emitter and a yellow phosphor plate. It has been shown that InGaN based blue LEDs could achieve external quantum efficiency in excess of 70% [1, 2]. However, this di-chromatic configuration typically has a poor color rendering index due to the lack of green and red components. The phosphor conversion process also limits the overall luminous efficiency due to energy loss during downconversion. To achieve luminous efficiency in excess of 200 lm/W and a color rendering index (CRI) in excess of 90, which is required for general illumination, a further improvement in blue LED efficiency and the use of tetra-chromatic configuration (blue + green + yellow + red) is necessary [3].* Unfortunately, the efficiency of both InGaN and AlInGaP LEDs decreases significantly in the green-yellow (500 - 580 nm) range. This efficiency gap is also known as “green gap”. Because AlInGaP materials have indirect bandgaps in this wavelength range, to achieve high-efficiency SSL, it is crucial to significantly improve the luminousNote that a trichromatic (e.g. blue + green + red) source cannot achieve a CRI > 90. efficiency of green and yellow InGaN LEDs. In this thesis, we will address these challenges using nano-structured GaN.Figure 1-1. Illustration of various potential white-light LEDs configurations (after Ref. [4]).1.3Limiting Factors for InGaN LEDs EfficiencyTo date, the efficiencies of InGaN LEDs are still limited by materials defects, polarization charges, and photon trapping. In this Section, we will briefly review the state of theart and overview how this research helps address these limitations.1.3.1 Materials DefectsAs mentioned before, the high defect density in GaN based materials grown on foreignsubstrates increases the non-radiative recombination rate and lowers the radiative efficiency. To date, several techniques have been demonstrated to improve the crystal quality and reduce the threading dislocation (TD) density of the GaN layer. Substrate pretreatmentat the growth temperature in an ammonia environment, also known as nitridation [5-7], has been shown to be critical for high quality GaN epilayers. The TD density of a typical GaN layer grown on c-plane sapphire substrate can be reduced to 108/cm2 [8] by employing the combination of a low temperature (LT; 450 - 600 °C)nucleation layer (NL) and a short annealing at the growth temperature to change the phase of the as-grown NL from cubic to hexagonal [9-11]. As will be discussed in Chapter 2, careful optimization of these low temperature growth sequences can significantly alter the subsequent GaN template growth. To this end, a home-made optical in situ monitoring tool (reflectometry) was established and will be discussed extensively in Chapter 2.In addition low temperature buffer growth, epitaxial lateral overgrowth (ELOG) which is a variation of selective area epitaxy (SAE) has been introduced [12, 13] to further lower the TD density by an order of magnitude to below 107/cm2. Variations of ELOG including pendeo- (from the Latin : hang on or suspended from) epitaxy (PE) [14] and multi-step ELOG are also effective to further reduce the TD density. Additional techniques such as TiN nano-porous network [15] and anodic aluminum oxide nano-mask [16] have also been proposed and demonstrated. All these methods, however, require ex situ processing and hence will add complexity and cost to the manufacturing. In this thesis, we will explore and generalize an in situ silane treatment approach to effectively lowering the TD density by an order of magnitude.1.3.2 Polarization ChargesDue to the non-cubic symmetry of GaN materials, compressively-strained active regions in InGaN LEDs exhibit both spontaneous and piezoelectric polarization charges. These polarization charges induce a strong internal electric field (IEF), typically on the order of MV/cm, in the active region, resulting in both efficiency droop at a high injection current density and the decrease of radiative efficiency with an increasing emission wavelength. The IEF can separate electrons from holes and increase electron leakage, resulting in low internal quantum efficiency (IQE) and efficiency droop [17], respectively. The suppression of the IEF, which is expected to increase IQE and the current density at which efficiency droop occurs, can be achieved by reducing the lattice mismatch in hetero-structures or growing them on semi-polar (e.g. {10-11} and {11-22}) and non-polar (e.g. a-plane and m-plane) surfaces. Because indium incorporation is more difficult on non-polar planes than on semi-polar planes, it is more advantageous to fabricate long-wavelength green-yellow LEDs on semi-polar planes to suppress the IEF.At least three approaches to fabricating semi-polar InGaN LEDs have been reported thus far. These include the growth of a GaN epilayer on spinel substrates [18], on bulk GaN substrates [19-27], and on the sidewalls of pyramidal or ridge GaN structures created on planar polar GaN surfaces using SAE [28-35]. GaN grown on spinel substrates have so far exhibited a high density of threading dislocations and stacking faults, thereby compromising the potential improvement of efficiency from the lowering of IEF. The use of bulk semi-polar GaN substrates has demonstrated the advantage of a lower IEF for the enhanced efficiency of green and yellow LEDs [25, 26]. However, limitations such as prohibitively high wafer cost and small substrate size need to be resolved before this approach can become more practical. On the other hand, the SAE technique can create semi-polar planes on polar GaN surfaces.High quality polar GaN films have been fabricated from a variety of substrates including sapphire, 6H-SiC, and bulk GaN by MOCVD. Using growth rate anisotropy and three-dimensional growth, different semi-polar and non-polar GaN planes can be generated on c-plane GaN [13]. In Chapter 3, we will show that high quality InGaN multiple quantum wells (MQWs) which exhibit IQE as large as a factor of three compared to polar MQWs can be grown on pyramidal GaN microstructures. This approach, however, requires ex situ patterning processes and does not easily produce a planar structure for electrical contacts. In this thesis, a new semi-polar LED structure is investigated, which is enabled by a novel epitaxial nanostructure, namely the nanostructured semi-polar (NSSP) GaN, which can be fabricated directly on c-plane GaN but without the issues of the SAE technique mentioned above [36]. NSSP GaN also eliminates the issues of excessive defects for GaN grown on spinel substrates and lowers the cost of using bulk semi-polar GaN substrates. As we will show later, the surface of NSSP GaN consists of two different semi-polar planes: (10-11) and (11-22). Therefore it is expected that InGaN active regions fabricated on NSSP GaN can exhibit a low IEF, and hence much improved IQE.1.3.3 Photon ExtractionAfter photons are generated from the active region in LEDs, they need to escape the device in order to be useful. When light travels from a medium with a higher refractive index to a medium with a lower refractive index, total internal reflection (TIR) occurs at the interface. In InGaN LEDs, photons experiencing TIR at LED surfaces can be re-absorbed by the active region or trapped in the device due to a wave-guiding effect as shown in Figure 1-2. In a simple InGaN LED, only 4% of photons generated from the active region can escape from each device surface. It has been shown that surface textures on LED surfaces can greatly reduce TIR and improve photon extraction efficiency as illustrated in Figure 1-2. To date, many surface texturing techniques such as photonic crystal structures [37] and photo-electrochemical etching of GaN surfaces [38] have been introduced. Notably, the photo-electrochemical etching of nitrogen-terminated GaN surface has been successfully implemented into commercial blue LEDs [2]. However, these approaches all require additional ex situ patterning processes which add significant costs.In this thesis, we investigate an in situ process to fabricate nano-structured GaN surfaces on LEDs which effectively improves the photon extraction efficiency. Figure 1-2. Light traveling within waveguides (left) with a smooth interface and (right) with a rough interface (after [39]).1.4 Organization of the ThesisThe objective of this thesis is to investigate cost-effective nanofabrication techniques that can significantly improve the efficiency of the state-of-the-art InGaN LEDs in both blue and green/yellow ranges for high performance solid-state lighting. The organization of this thesis is as follows.In Chapter 2, a summary of the MOCVD techniques for InGaN LEDs is given. In Chapter 3, we study the dependence of InGaN LED IQE on {10-11} semi-polar planes using SAE. In Chapter 4, fabrication and characterization of novel andcost-effective nano-structured GaN templates will be described. Using in situ silane treatment (ISST) and high temperature overgrowth (HTO), the formation of nano-scale inverted cone structures and nano-structured semi-polar (NSSP) templates has been obtained. In Chapter 5, we study InGaN semi-polar LEDs based on NSSP templates. An improvement of internal quantum efficiency is demonstrated.A green semi-polar InGaN LED grown on a c-plane substrate is also demonstrated. In Chapter 6, current spreading in NSSP InGaN LEDs will be discussed. In Chapter 7, the application of ISST for theimprovement of photon extraction efficiency of an InGaN LED will be discussed. In Chapter 8, we will summarize and make suggestions for future work.2.1 Gallium Nitride GrowthAs mentioned in the Introduction, gallium nitride (GaN) and related alloys are excellent candidates for future solid-state lighting. To date, III-nitride epitaxial growth has been limited by the lack of sufficiently large single crystal substrate for homoepitaxial growth. Therefore, the growth of GaN and related materials has been largely based on hetero-epitaxy using hydride vapor phase epitaxy (HVPE), metal organic chemical vapor deposition (MOCVD), and molecular beam epitaxy (MBE). Among these techniques, MOCVD is the leading technology due to the advantages on material quality, scalability, and cost [40]. The material quality of GaN grown by MOCVD has been excellent owing to its relatively high growth temperature (1000 - 1200°C) [41, 42].To date, various substrate materials including sapphire (Al2O3), silicon carbide (SiC), and silicon have been studied for GaN growth (Table 2-1). Although GaN substrates have been recently introduced in markets through bulk material growth on foreign substrates using HVPE and laser cutting along specific crystal planes, the cost has been prohibitively high. On the other hand, GaN grown on c-plane (0001) sapphire substrate exhibits stable growth over a wide range of growth conditions despite high dislocation density at the interface between thesubstrate and epitaxial layer. In this research, I have helped ramping up an MOCVD system together with Dr. Hongbo Yu. In this Chapter, I will summarize the MOCVD technologies and defect reduction strategies for InGaN light-emitting diodes (LEDs) epitaxy that will be used throughout this Thesis.2.1.1 GaN Growth Using MOCVDDue to a large lattice mismatch between GaN and sapphire, it is important to contain the defects near the GaN/sapphire interface such that the defect density can be minimized in the device region. Such optimization is achieved using in situ reflectometry [44, 45]. A home-made reflectometry system shown in Figure 2-1 was established in our 3 x 2” Thomas-Swan Close-Coupled Showerhead (CCS) MOCVD system. White light is reflected from the sample surface and monitored by a spectrometer during the growth. The reflectivity is sensitive to both the surface morphology and the epitaxial layer structure.Figure 2-1. Illustration of a home-made in situ reflectometry system integrated into the MOCVD system.Figure 2-2. Typical growth conditions for GaN templates used in this research.Typical growth conditions for GaN templates used in this research are summarized in Figure 2-2 and Table 2-2. Unless otherwise mentioned, c-plane sapphire substrates were used. The five steps outlined in Table 2-2, including high temperature (HT) cleaning, nitridation, low temperature (LT) nucleation, annealing of LT nucleation layer, and HT GaN growth, are crucial for high quality GaN epilayer.Figure 2-3 and Table 2-3 show the corresponding in situ reflectometry signal.In the following, we will describe how the reflectometry signal can be used to optimize the GaN template growth. Unless otherwise mentioned, we will refer to the reflectometry signal shown in Figure 2-3.Figure 2-3. In situ reflectometry trace of GaN template growth (Sample ID : UM-S07- 254). The highlighted areas correspond to important sub-steps during the epitaxy.2.1.1.1 High Temperature CleaningInitially, as the sample temperature is ramped up, the reflectivity increases due to the increase of the refractive index of the sample. Kim et al. has thoroughly studied the effect of initial thermal cleaning on the sapphire substrate andexperimentally demonstrated that this thermal treatment can effectively reduce the surface roughness of the substrate [46]. Generally, the flat surface is preferred for the GaN nuclei to be formed uniformly, which is critical to the crystal quality of the final GaN epilayer. The specific condition for the HT cleaning should be optimized by examining the treatment temperature and time. In our GaN growth, the optimal treatment temperature and time were set to be 1075 °C and 5 minutes, respectively. Moreover, HT surface annealing can effectively eliminate surface moisture.2.1.1.2 NitridationNitridation [5, 7] is the process of NH3 preflow under hydrogen (H2) ambient to prepare the surface for growth. During nitridation, NH3 reacts with the surface oxygen atoms on the sapphire substrate. Due to the replacement of the oxygen atoms by the nitrogen atoms and the diffusion of the nitrogen atoms into a certain depth, the exposed surface becomes a smooth amorphous state. Because this change of surface morphology is on the order of tens of angstrom, the corresponding reflectivity change is not significant. It has been shown that with a proper nitridation condition, GaN epilayers with lower dislocation density and better electrical and optical properties can be achieved [7]. However, as mentioned above, suitable combination of reactor conditions such as temperature, treatment time, and NH3 flow rate must be considered. In our GaN growth, the nitridation was optimized at 530 °C for a total of 210 seconds under 3 slm of NH3 flow.2.1.1.3 Low Temperature NucleationAs mentioned in Section 1.3.1, several approaches have been introduced to reduce the threading dislocation (TD) density in growing the GaN template. Specifically, the use of low temperature nucleation layer (LT NL) has been shown to be simple yet effective. A threading dislocation density as low as 108/cm2 has been reported [8].As GaN is nucleated on sapphire, the cubic phase islands are first formed at a temperature of 450 - 600 °C. These islands are subsequently transformed into the wurtzite phase [8]. The increase of the reflectivity during the LT NL growth is attributed to the increase of reflection from the flat top surfaces of nuclei. Basically, we know that the reflection from GaN is about twice stronger than that from sapphire due to the difference in refractive indices. As the islands become denser (i.e. the growth time of LT NL becomes longer), total reflection from the top surface of nuclei becomes up to 200% of reflection from sapphire substrate assuming that the entire surface is covered by GaN islands. Even though the islands are not coalesced completely to form a crystalline layer, this is still possible because the distances between the adjacent islands are too small compared to the optical wavelength. Once the reflectance exceeds twice that of the sapphire (as shown in Figure 2-3), the islands continue to coalesce further, which results in larger GaN grains and a thicker NL. Here, the size of the nucleation islands and the thickness of the NL are critical to obtain high quality GaN epilayer. To show that, we have compared a series of GaN templates with different NL conditions. All conditions were kept the same† except the growth time of the LT NL was varied,resulting in different LT NL thicknesses. The thickness of the LT NL was extrapolated by analyzing the reflectometry data as the reflection ratio at the end of LT NL growth to the sapphire substrate (RLT NL / RSapphire). The qualities of the GaN templates were characterized using photoluminescence (PL) and x-ray diffraction (XRD). From these results, the best GaN template quality can be obtained when RLT NL / RSapphire is around 2.6 which corresponds to a 40nm thick NL, at the given growth conditions.† LT NL growth temperature = 530°C, V/III = 9140, LT NL annealing time = 420 seconds, HT GaN growth temperature = 1040°C, V/III = 1230, growth time = 4300 seconds.Figure 2-4. The comparison of GaN template qualities with respect to the reflection ratio between the LT NL surface and the sapphire substrate.2.1.1.4 Annealing of Low Temperature Nucleation LayerIn GaN hetero-epitaxy with a large lattice mismatch, the initial growth on the surface follows the Volmer Weber model [47], i.e. GaN island growth dominates. In order to obtain smooth GaN templates, these islands need to be transformed into the layer-by-layer growth mode using an NL annealing process. During annealing, the substrate temperature is gradually increased up to around 1030 - 1050 °C under NH3 overpressure. Temperature ramping rate, reactor pressure, and NH3 flow can control the NL decomposition rate, which determines the surface roughness at the end of the annealing process [48, 49]. In Figure 2-3, after point (h) at which LT NL annealing begins, slight increase of reflectance is normally observed. The increase continues until around 800 °C at which GaN decomposition process starts to occur. Once the reflection intensity peaks, it begins to drop due to the increase in surface roughness. Initially randomly distributed islands start to be transformed into relatively uniform islands due to the decomposition of the NL and the migration of the gallium ad-atoms.During the annealing process, the reflectivity first decreases due to the increase of surface roughness. Further annealing results in a slight increase of reflectivity because at a higher temperature, the surface morphology becomes smoother. However, if we anneal the surface even further, the surface roughness increases again, which results in the decrease of reflection intensity [48, 49]. This phenomenon can be explained by considering the volume of the GaN islands. At the transition point ((k) in Figure 2-3), the volume of the islands per unit area becomes the highest which is preferable for the subsequent HT GaN growth. As a rule of thumb, the position of this (reflectometry trace) shoulder is dominated by the highest temperature of the annealing process [50]. In summary, the goal of the low temperature nucleation and the subsequent annealing is to achieve a surface morphology with proper density and sizes of the islands for the following HT GaN growth.As shown in Figure 2-5, even a slight change of the island distribution caused by a slight difference of the NL thickness and temperature ramping rate (Table 2-4) can result in a significant difference in the following HT GaN growth under the same conditions. In general, it takes longer for an NL with a rougher surface and smaller islands to be transformed into the 2D growth mode. The conditions to achieve high crystal quality GaN on sapphire are mostly related to the growth and annealing of the LT NL.2.1.1.5 HT GaN GrowthAs soon as the sapphire surface is covered with suitable volume, uniformity, thickness, and density of GaN islands, HT GaN growth can be followed. This HT GaN itself can be divided into two parts (Figure 2-6). Part I corresponds to the initial stage of HT GaN growth when the growth mode is transitioned from 3D to 2D, which affects the crystal quality significantly. In part II, GaN epilayer becomes thicker because the growth mode as well as growth condition is stabilized for 2Dmode. Several strategies to control the GaN growth in each regime will be briefly discussed in the following.The growth in part I is a buffer step to prepare a surface suitable for HT GaN growth. During this step, the oscillation of the reflectometry signal becomes increasingly obvious. Initially, the reflectivity continues to drop due to the increase of surface roughness induced by the coagulations of the islands, i.e. 3D growth. As time goes by, the 3D growth mode is suppressed and the 2D growth mode is enhanced. Once the surface becomes flattened due to the enhanced 2D growth, layer by layer growth of GaN begins, which causes the reflectivity to increase. The duration of this part of growth can be optimized by tweaking the reactor pressure, V/III ratio, and growth rate [51, 52]. For example, in the case of a low V/III ratio, it takes longer to recover the reflection intensity, which implies that the change of the growth mode (3D 2D) occurs more slowly. The reflectivity recovery time is critical to oscillation amplitude in part II. In general, a larger oscillation amplitude corresponds to a better crystal quality.The part II of the HT GaN growth is stable in a wide range of growth conditions because the growth occurs in a mass transfer limited region. Nevertheless, several key factors will still affect the crystalline structure, including the growth temperature, trimethyl-gallium (TMG) flow, NH3 flow, V/III ratio, and reactor pressure. As shown in Figure 2-7, the growth rate increases as the group III flow increases but decreases as the V/III ratio and growth temperature increase. The。
毕业设计外文资料翻译
理工学院毕业设计外文资料翻译专业:通信工程姓名:张聪学号: 13L0751243外文出处: Organic Electronics(用外文写)2017年3月4日附件: 1.外文资料翻译译文;2.外文原文。
有效激发复合体有机发光二极管与双极型受体1.介绍因为他们发现,如何有效地利用产生电三线态激子辐射衰变总是在研究领域最具挑战性的问题之一有机发光二极管(OLED)。
根据选择的规则推导出量子自旋统计,在有机半导体设备,只有1/4 产生电激子的分数的单重态可以利用辐射衰变,而其他3/4的三重态激子是浪费的无辐射衰变由于量子自旋禁止原则。
这个结果在理论上最大辐射激子比(gr)25%的常规荧光发射。
整合的策略有机金属荧光粉的发射器打破了自旋禁止原则的广泛证明理论单位gr由于自旋轨道耦合效应引起的重金属原子。
然而,稀有金属的高成本在有机金属化合物仍是商业的一大障碍与有机金属发射器OLED的应用。
连续的研究工作一直致力于发展不含金属的廉价有机发射器使用单线态的能力和三线态激子辐射衰变。
最近,关注一直在支付上变频机制通过三重态-三联体毁灭(TTA)或反向系统热激活穿越(RISC)方法来获得这个目标。
考虑到所有的电可以产生生成的三线态激子单重态,100%的理论最大gr是可能的OLED的包括热激活延迟荧光(TADF)发射器通过RISC过程,理论上最大gr的OLED包含TTA发射器是有限的为62.5%(25% + 75% / 2)。
这表明TADF化合物大大有有前途的潜在开发高效的OLED。
事实上,TADF 排放迅速发达,各种高效RGB和白色组成的OLED TADF gr发射器远高于25%的报告。
TADF过程,能量差之间单线态激发态(S1)和最低三重激发态(T1)排放应该最小化等于或小于热能在室温下(25兆电子伏),一旦三联体激子在TADF分子产生电场,他们可以很容易地产生辐射S1状态协助环境热能。
一个单位的内部量子效率的有机组成TADF 发射器是如此理论上可行。
经典OLED培训教材
OLED显示技术简介OLED(Organic Light-Emitting Diode,又称有机电激发光显示、有机发光半导体)是有机发光二极管的英文缩写。
其是一种利用多层有机薄膜结构产生电致发光的器件,它很容易制作,只需要低的驱动电压,这些特征使得OLED在满足平面显示器的应用上显得非常突出。
OLED显示屏比LCD更轻薄、亮度高、功耗低、响应快、清晰度高、柔性好、发光效率高。
与LCD(Liquid Crystal Display)相似,OLED的驱动背板也分为有源驱动(AMOLED-Active Matrix OLED)和无源驱动(PMOLED-Passive Matrix OLED)两种。
其中PMOLED的驱动方式较为落后,需要对整个背板进行扫描,当面积大时刷新率变慢、电流降低,难以实现高分辨率、大面积和高亮度,仅能用于较低端的小屏幕产品;AMOLED是目前的主流技术,通过LTPS-TFT (Low Temperature Poly-Si Thin Film Transistor),即低温多晶硅薄膜晶体管,对每个像素精确控制进行驱动。
该驱动技术与目前市面流行的TFT-LCD 一致。
OLED与LCD相比,其最大的特点就在于自发光,无需背光源,该特点带来了许多优点:自发光带来的色域控制、视角控制都要优于LCD;由于不需对光路进行偏振,因此发光效率也显著提高、响应时间快、对比度高、功耗低;去除了背光源有效降低质量、减薄厚度;而且现在的技术可以将电路板涂布在柔性薄膜上,将整个OLED显示屏柔性化,这是LCD所不能做到的。
这些性能上面的优势可以满足许多新兴出现的消费需求,使得OLED成为发展迅猛的新一代显示技术。
OLED(OrganicLight-Emitting Diode),又称为有机电激光显示、有机发光半导体(OrganicElectroluminesence Display,OLED)。
OLED属于一种电流型的有机发光器件,是通过载流子的注入和复合而致发光的现象,发光强度与注入的电流成正比。
《科技英语阅读》课后名词解释和翻译
Unit1 mathematics名词解释绝对补集absolute complement / 代数algebra /代数式algebraic expression / 代数方程algebraic equation / 代数不等式algebraic inequality / 任意常数arbitrary constant / 数组array / 底数;基数base number / 连续函数continuous function / 函数function / 复合函数function of function / 函数记号functional notation / 集合aggregate / 子集subset /迭代函数iterative function/优先权之争priority battle/分形特征fractal properties/有意义make sense/以越来越小的规模重复同一模式patterns repeat themselves at smaller and smaller scales/混沌理论chaos theory/季刊a quarterly journal/数学界the mathematics community/波纹线crisp lines/会议公报proceedings of a conference翻译3. Translate the sentences into Chinese.1)他主要是因为用分形这个概念来描述(海岸线、雪花、山脉和树木)等不规则形状等现象而闻名于世,这些不规则形状在越来越小的规模上不断重复同一模式。
2)如果再仔细观察,就可以发现集的边界并没有呈波纹线,而是像火焰一样闪光。
3)但是,克朗兹在这场辩论中引入了一个新东西,他说曼德布洛特集不是曼德布洛特集发明的,而是早在“曼德布洛特集”这个术语出现几年以前就已经明确地在数学文献中出现了。
4)曼德布洛特同时也暗示即使布鲁克斯和马特尔斯基的论文先于他发表,但因为他们没有领会到其价值,仍然不能将他们看作是曼德布洛特集的发现者。
OLED技术及发展
OLED技术及发展摘要:OLED即英文Organic Light Emitting Diode的缩写,中文译作有机发光二极管。
因为具备轻薄、省电等特性,因此从2003年开始,这种显示设备在MP3播放器上得到了广泛应用,而对于同属数码类产品的DC与手机,此前只是在一些展会上展示过采用OLED屏幕的工程样品,还并未走入实际应用的阶段。
但OLED屏幕却具备了许多LCD不可比拟的优势,因此它也一直被业内人士所看好。
Abstract:Since the breakthrough by Kodak in 1987, organic light-emitting diodes (OLEDs)have been seen as one of the most promising technologies for future displays. A number of materials have been developed and improved in order to fulfill the requirements of this application. The materials differ from one another by their structure but also by the mechanism involved in the electroluminescence produced (fuorescence versus phosphorescence). When properly stacked, these materials result in a device that can achieve the required high efficiency and long lifetime. Such red, green and blue devices can then be combined in matrices to become the core of a display. Building up these structures onto a display backplane is one of the challenges facing the industry. The circuitry for driving the pixels can be adapted to the OLED,sometimes at the expense of the simplicity of the display, but bearing in mind that the fabrication process must remain industrially viable.[4]1. 简述:OLED:Organic Light Emitting Display,即有机发光显示器,在手机LCD上属于新崛起的种类,被誉为“梦幻显示器”。
光电信息工程外文翻译文献
光电信息工程外文翻译文献(文档含中英文对照即英文原文和中文翻译)译文:气体温度通过PECVD沉积对Si:H薄膜的结构和光电性能的影响摘要气体温度的影响(TG)在等离子体增强化学气相沉积法(PECVD)生长的薄膜的结构和光电特性:H薄膜已使用多种表征技术研究。
气体的温度被确定为制备工艺的优化、结构和光电薄膜的性能改进的一个重要参数。
薄膜的结构性能进行了研究使用原子力显微镜(AFM),傅立叶变换红外光谱(FTIR),拉曼光谱,和电子自旋共振(ESR)。
此外,光谱椭偏仪(SE),在紫外线–可见光区域的光传输的测量和电气测量被用来研究的薄膜的光学和电学性能。
它被发现在Tg的变化可以修改的表面粗糙度,非晶网络秩序,氢键模式和薄膜的密度,并最终提高光学和电学性能。
1.介绍等离子体增强化学气相沉积法(PECVD)是氢化非晶硅薄膜制备一种技术,具有广泛的实际应用的重要材料。
它是用于太阳能电池生产,在夜视系统红外探测器,和薄膜晶体管的平板显示装置。
所有这些应用都是基于其良好的电气和光学特性以及与半导体技术兼容。
然而,根据a-Si的性质,PECVD制备H薄膜需要敏感的沉积条件,如衬底温度,功率密度,气体流量和压力。
许多努力已经花在制备高品质的薄膜具有较低的缺陷密度和较高的结构稳定性的H薄膜。
众所周知,衬底温度的强烈影响的自由基扩散的生长表面上,从而导致这些自由基更容易定位在最佳生长区。
因此,衬底温度一直是研究最多的沉积参数。
至于温度参数在PECVD工艺而言,除了衬底温度,气体温度(Tg)美联储在PECVD反应室在辉光放电是定制的a-Si的性能参数:H薄膜的新工艺。
事实上,TG PECVD系统的变化可以影响等离子体的能量在辉光放电,并最终改变了薄膜的性能。
根据马丁吕,当薄膜制作接近前后颗粒的形成机制在a-Si∶H薄膜,薄膜性能对TG的相关性比衬底温度更为显著。
然而,大多数的研究到目前为止只集中在衬底温度的影响。
在我们以前的研究中,我们报道的气体温度对磷的结构演化的影响掺杂的a-Si∶H薄膜的拉曼光谱。
电子产品英文翻译
电子产品英文翻译Electronic ProductsWith the rapid advancement of technology, electronic products have become an integral part of our daily lives. From smartphones to laptops, televisions to smartwatches, electronic devices have revolutionized the way we communicate, work, and entertain ourselves.One of the most popular electronic products is the smartphone. Packed with features such as internet access, GPS navigation, and high-quality cameras, smartphones have become essential for staying connected and organized. They enable us to easily communicate with others through calls, text messages, and social media platforms. Moreover, smartphones provide us with a wide range of entertainment options, from streaming movies and music to playing games.Laptops are another indispensable electronic product. They are portable and offer us the flexibility to work or study from anywhere. Laptops are equipped with powerful processors, ample storage space, and high-resolution displays, which allow us to multitask and perform demanding tasks. With access to the internet, we can browse websites, send emails, create documents, and access cloud storage.Televisions have also undergone significant transformations in recent years. Traditional cathode ray tube TVs have been replaced by sleek and slim LED and OLED televisions. These modern TVs offer high-definition picture quality, vibrant colors, and wideviewing angles. Many televisions have built-in apps and internet connectivity, enabling us to stream our favorite movies, TV shows, and videos directly from online platforms.Smartwatches represent another innovation in the electronic product market. These wearable devices have gained popularity due to their health and fitness tracking features. Smartwatches allow us to monitor our heart rate, count our steps, track our sleep patterns, and receive notifications from our smartphones on our wrists. Additionally, smartwatches can be customized with various watch faces and straps to suit our individual preferences.Electronic products have greatly improved our lives, making us more connected and efficient. However, it is important to keep in mind that excessive use of electronic devices can have negative effects. Spending too much time staring at screens can lead to eye strain, poor posture, and disruption of sleep patterns. It is crucial to strike a balance between utilizing electronic products for their advantages and taking breaks to engage in physical activities and interact with others.In conclusion, electronic products have become an integral part of our lives and have transformed the way we communicate, work, and entertain ourselves. From smartphones to laptops, televisions to smartwatches, these devices offer us convenience, connectivity, and entertainment. However, it is important to use them in moderation and be mindful of their potential negative effects on our health and well-being.。
OLED外文文献翻译
ITO表面经过常压等离子体处理的有机发光器件的特性Chang Hyun JEONG, June Hee LEE, Y ong Hyuk LEE, Nam Gil CHO, Jong Tae LIM,Cheol Hee MOON and Geun Young YOMEDepartment of Materials Science & Engineering, Sungkyunkwan University, Suwon, 440-746, Korea PDP Division, Samsung SDI Co., Ltd., Cheonan, 330-300, Korea(Received October 4, 2004; accepted October 28, 2004; published December 10, 2004)摘要:本课题研究了ITO表面经过He/O2和He/SF6的常压等离子混合气体处理后的影响和有机发光器件的电学特性。
经过He/O2或He/SF6的等离子体处理后,由ITO/2-TNATA/NPD/Alq3/LiF/Al组成的OLED 器件显示出了很好的电学特性,例如:较低的导通电压,高的功率效率等等。
经过He/SF6处理的器件与He/O2处理过的相比有更卓越的电学性能。
在用He/O2和He/SF6等离子体处理后,改善后的电性能与碳元素的减少和ITO表面Sn4+的聚集以及ITO中氟元素的掺杂浓度有关,这表明表面处理后工作性能有所提高。
关键词:ITO,表面处理,常压等离子体,OLED,He/O2,He/SF6OLED显示器件之所以能得到广泛的研究是因为他们具有非常优越的特性,例如:快速的响应时间,较低的工作电压,较高的量子效率等等。
此外,与其他的平板显示器相比,例如:液晶显示器和等离子显示器,OLED显示器有更简单的工艺流程和更低的制造成本。
目前,对于基板尺寸小于370mm*470mm 的器件,通常在一个真空腔体内利用多层蒸发技术来完成,而用于制造接近920mm*730mm的大尺寸的沉积技术目前正处于研发当中。
毕业论文外文文献翻译LaserD...
毕业论⽂外⽂⽂献翻译LaserD...毕业设计(论⽂)外⽂⽂献翻译⽂献、资料中⽂题⽬:⽂献、资料英⽂题⽬:激光显⽰器的设计与制作⽂献、资料来源:Laser display design and production ⽂献、资料发表(出版)⽇期:院(部):专业:班级:姓名:学号:指导教师:翻译⽇期: 2017.02.14Laser display design and productionDisplay technology is the use of electronic technology to provide flexible transform visual information technology.Laser display technology, known as the fourth generation" revolutionary" display technology of laser display technology, known as the fourth generation" revolutionary" display technology. Laser display is widely used in TV, projector, public information screen, digital cinema, home theater, pilot training, big screen command display system, water curtainimaging performances and other fields, in the successful realization of miniaturization, but also can be applied in mobile phone projection, individualized helmet display system.ProspectReportedly, the display industry is an important part of information industry. Laser display with high color saturation and three color laser as the display light source, a color gamut range, long service life, environmental protection, energy-saving advantages, so that the display system comprehensive performance substantially span, is considered to be" a revolution in the field of display".Laser display colors, color performance ability is flat TV 2 ~ 3 times; the service life is flat TV light source more than 10 times; the production process is environmentally friendly, no waste water, waste gas, waste discharge. In addition, the laser source is the core device composed of semiconductor material, each 18 months performance can be doubled and the cost is reduced by half, its cost reduction potential is tremendous." These advantages make the laser display to the rapid speed of development.ProspectReportedly, the display industry is an important part of information industry. Laser display with high color saturation and three color laser as the display light source, a color gamut range, long service life, environmental protection, energy-saving advantages, so that the display system comprehensive performance substantially span, is considered to be" a revolution in the field of display".Laser display colors, color performance ability is flat TV 2 ~ 3 times; the service life is flat TV light source more than 10 times; the production process is environmentally friendly, no waste water, waste gas, waste discharge. In addition, the laser source is the core device composed of semiconductor material, each 18 months performance can be doubled and the cost is reduced by half, its cost reduction potential is tremendous." These advantages make the laser display to the rapid speed of development.Current situation analysisThe domestic status quoChinese laser display technology level completely in sync with the world. In China the concept first laser display, laser display technology leader, academician of Chinese Academy of Engineering Xu Zuyan under the leadership of academician, laser display technology research projects after 3 National 863 project, and contained more than 10, in 2003 to obtain major breakthrough, has launched many generation of laser TV principle prototype. In 2006 the group completed the research phase of the mission objectives, 2007 laser display technology begins to enter industrialization stage.Foreign statusAs the" next generation" display technology competition the focal point, SONY, Panasonic, Hitachi, Toshiba, Mitsubishi, EPSON, Samsung and other well-known international showed giant, have increased in the laser display field development. Since 2005 there have been many companies introduce laser television concept prototype. According to the United States of America" laser focus world" professional media optimistic forecasts, 2010 before and after laser display technology in the world will form a $57000000000 / year in industrial scale.In recent years, the International German, Japan and the United States, South Korea and other countries have invested enormous human and material resources for the full color laser display technology research. Japanese industry calls it" the human visual revolution in history", and to the power of the state, a well-known multinational companies to participate in joint development. In 2005, the Japanese Sony company in Aichi Expo launched a large-scale laser theater, show its technology development achievement; 2006 March, Japan Seiko Epson Corporation announced and the United States Novalux strategic cooperation, commondevelopment of laser display technology; 2006 February, Japan's Mitsubishi Electric announced the launch of laser TV prototype, and initially set up the industrialization program, to seek in the the future high technology competition to occupy the strategic commanding elevation. Laser show beyond all dispute to become a monochrome display, color display, digital display after the next generation display technology.Different display devices based on different physical principles. Any electronic display method is to change the optical properties of certain. Active display device is the device of self-luminous display device; passive by external light irradiation and the realization of display. There are a number of display method is the use of light refraction, diffraction and polarization to achieve.Display device:Display device by a display device and relevant circuits, used by the display device can be divided into different, electron beam display device, flat panel display device and projection type display device. The display processor is constituted of a display device is an important component, its function is to buffer, timing, control and coordinate transformation, data insertion and deletion, image changes, rotation, shift and various other data control. The display processor includes a refresh memory, its capacity to accommodate one or more digital data, to fit the vision requirements. In a display device such as a keyboard input device, a graphics tablet,,, trackball and lever, is man machine combination method, used to strengthen the function of display device.Laser is a kind of energy is highly concentrated, highly monochromatic coherent light source, with several different color, in a display of attention. In the military and public place of entertainment, use of the holographic principle can form stereoscopic image holographic display. However, the practical application of laser display by the light intensity and efficiency of a certain limit.Display software:In a computer controlled display device, display software is an important component in a computer system, is based on the software compiled. Interactive display device capable of interacting by the graphic software. Interactive graphic display software generally consists of basic graphics software, special graphics software and application software is composed of three parts. In a display system in certain applications, requires the application ofthree-dimensional rotation technique. 3D rotation, zoom and cross-sectional profile technique in medical, construction design and mechanical design display applications is very useful, is a complicated problem to display software.Display system:Depending on the application, by one or more, one or a plurality of display device is composed of the availability of visual information electronic system. It received from various electronic equipment or system signal. Display system generally need to be equipped with the appropriate input device and the necessary recording equipment, in order to realize man machine contact and for later investigation by.Electron beam tube display device in display technique is still occupied the main position, but all board or wall display device (i.e., a matrix display ) superiority, will get developing quickly. Projection display technology has been flat screendisplay replaces the trend. Display software in intelligent display device is very important. Graphic language standardization, the wide application of computer display has a huge impact, thus great attention. Computer display technology development will promote the development of display software.A new image reconstruction technology makes full use of the advantages of the laser itself. In the light of the dissemination method, laser light source with the traditional incandescent lamp has a fundamentally different: ordinary incandescent light in all directions。
OLED 的前世今生和优缺点
谈谈OLED屏的前世今生及其优缺点2017-10-16OLED的前世今生有机发光二极管(英文:Organic Light-Emitting Diode,缩写:OLED)又称有机电激发光显示器(英文:Organic Electroluminescence Display,缩写:OELD)、有机发光半导体,与薄膜晶体管液晶显示器为不同类型的产品,前者具有自发光性、广视角、高对比、低耗电、高反应速率、全彩化及制程简单等优点,但相对的在大面板价格、技术选择性、寿命、分辨率、色彩还原方面便无法与后者匹敌,有机发光二极管显示器可分单色、多彩及全彩等种类,而其中以全彩制作技术最为困难,有机发光二极管显示器依驱动方式的不同又可分为被动式(Passive Matrix,PMOLED)与主动式(Active Matrix,AMOLED)。
有机发光二极管可简单分为有机发光二极管和聚合物发光二极管(polymer light-emitting diodes,PLED)两种类型,目前均已开发出成熟产品。
聚合物发光二极管相对于有机发光二极管的主要优势是其柔性大面积显示。
但由于产品寿命问题,目前市面上的产品仍以有机发光二极管为主要应用。
最初观察到有机材料中电致发光现象的是二十世纪五十年代André Bernanose和他在法国南茜大学的同事,1960年,Martin Pope 和他在纽约大学的一些同事开发了与有机晶体接触的欧姆暗电极( ohmic dark-injecting electrode)。
他们进一步描述了空穴注入电极触点和电子注入电极触点所需的能量需求。
这些正是所有现代OLED器件中电荷注入的基础。
Pope的小组还首次通过在400伏特电压下使用一小块银电极,观察到了单一纯蒽晶体和掺有并四苯的蒽晶体在真空下的直流电致发光的现象。
并提出了场加速电子励磁分子荧光的机制。
ēn(Anthracene)蒽,俗称绿油脑,一种稠环芳香烃,分子式C14H10,分子量178.22。
OLED面板制造流程(全英文)
Manufacturing Process
Manufacturing Process
Manufacturing Process
Deposition – Liner Source
Manufacturing Process
Manufacturing Process
Deposition – Cathode
Manufacturing Process
Deposition – Transparent Cathode
Basic Process
Material
Deposition Pre-treatment
Cleaning ITO sputtering
Encapsulation – Lid
乾燥劑
封裝蓋 OLED元件
封裝膠
玻璃基板
Manufacturing Process
In Dry Box
Manufacturing Process
Encapsulation – Passivation
Overcoat OLED
Silicon Nitride (SiNx) Silicon Oxynitride (SiON, 100nm)
Substrates Preparation - Pixelation
Short (leakage current)
Cathode Organic layers Insulator ITO Glass
Manufacturing Process
Substrates Preparation - Cathode separator(Rib)
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ITO表面经过常压等离子体处理的有机发光器件的特性Chang Hyun JEONG, June Hee LEE, Y ong Hyuk LEE, Nam Gil CHO, Jong Tae LIM,Cheol Hee MOON and Geun Young YOMEDepartment of Materials Science & Engineering, Sungkyunkwan University, Suwon, 440-746, Korea PDP Division, Samsung SDI Co., Ltd., Cheonan, 330-300, Korea(Received October 4, 2004; accepted October 28, 2004; published December 10, 2004)摘要:本课题研究了ITO表面经过He/O2和He/SF6的常压等离子混合气体处理后的影响和有机发光器件的电学特性。
经过He/O2或He/SF6的等离子体处理后,由ITO/2-TNATA/NPD/Alq3/LiF/Al组成的OLED 器件显示出了很好的电学特性,例如:较低的导通电压,高的功率效率等等。
经过He/SF6处理的器件与He/O2处理过的相比有更卓越的电学性能。
在用He/O2和He/SF6等离子体处理后,改善后的电性能与碳元素的减少和ITO表面Sn4+的聚集以及ITO中氟元素的掺杂浓度有关,这表明表面处理后工作性能有所提高。
关键词:ITO,表面处理,常压等离子体,OLED,He/O2,He/SF6OLED显示器件之所以能得到广泛的研究是因为他们具有非常优越的特性,例如:快速的响应时间,较低的工作电压,较高的量子效率等等。
此外,与其他的平板显示器相比,例如:液晶显示器和等离子显示器,OLED显示器有更简单的工艺流程和更低的制造成本。
目前,对于基板尺寸小于370mm*470mm 的器件,通常在一个真空腔体内利用多层蒸发技术来完成,而用于制造接近920mm*730mm的大尺寸的沉积技术目前正处于研发当中。
此外,利用喷墨打印技术代替真空蒸发技术来制作高分子有机OLED 器件正处于积极的研发阶段。
对于OLED器件,需要一种透光性高的透明导体,在各种透明导体中,具有高传导性和高透光性的ITO被广泛的应用。
为形成OLED器件,有机材料被沉积在ITO上,形成一个低阻值的欧姆接触,OLED 器件在ITO和有机材料之间形成的接触电阻可以通过ITO表面预处理来改变。
ITO是一个非化学计量化合物,化学成分可以很容易的改变。
因此,为了改善OLED器件中ITO和有机材料间的接触特性,在ITO表面沉积有机材料之前进行处理是非常重要的。
作为表面处理方法的低压等离子技术、UV/O3技术、和湿处理均被用于去除有机杂质和改善ITO表面特性。
然而,这些技术价格非常昂贵,而且低压等离子技术和UV/O3技术难以用于规模较大的基板,并且,湿处理法还存在环境问题。
为了代替低压等离子体技术和湿处理等技术,以常压等离子体,如电晕放电、电介质阻挡放电、大气等离子流体等为处理技术来处理电子材料、电极材料、生物材料和结构材料的方法正在积极地开发当中。
本课题研究了利用常压等离子体来处理和清洁OLED器件ITO玻璃表面的价值。
作为常压等离子清洁技术,即一个修改了的DBD技术,能被用于大规模的环境中并且展现了一个比传统DBD更高密度的等离子体。
通过改变在修改的DBD混合气体,这些混合气体在ITO的表面特性和形成干净的ITO 玻璃的OLED器件电学特性方面的影响正在观察中。
图1为处理ITO玻璃表面的常压等离子体设备图。
如图所示,修改过的DBD的研究设备由代替一个平板电极作为功率电极的锥体形状的多针电极,作为接地端的另一块平板电极以及两电极间的电介质材料组成。
使用多针电极代替平板电极,通过在针的尖端形成一个类似于具有较高稳定性的电晕放电和辉光放电的高电场,从而能够获得一个高的离子体密度和低压交流下的气体击穿。
多针功率电极连接到频率为20~30千赫兹、电压为3~15千伏的交流电压,平板接地电极接地。
He(10 slm)/O 2(3 slm) 和He(10 slm)/SF 6(100 sccm)的混合气体被应用于OLED 器件ITO 表面的清洗。
在等离子处理前,所有的ITO玻璃均用有机溶剂清洗过。
这些气体的最佳成分通过接触角和ITO 基板碳含量来选择,接触角利用专用工具来测量,碳含量通过改变由0~3 slm 的氧流速、0~500 sccm 的SF 6流速以及10slm 的氦流速的X射线光电谱线来测量。
交流电源为25千赫兹、10千伏,持续工作30秒。
经过He/O 2和He/SF 6等离子混合气体清洁后的ITO 表面组成用X 射线源为1486.6 eV 的X 射线光电子能谱来研究。
在没有破坏真空的条件下,通过在洁净的ITO 上OLED 材料的热分解和电极材料的顺序蒸镀制备成了OLED 器件。
研究的这个OLED 器件的结构为ITO/2-TNATA(60 nm)/NPD(20 nm)/Alq 3(40 nm)/LiF(1nm)/Al(100 nm)。
有机材料、氟化锂和铝的沉积速率分别为0.3–0.5 A o /s 、0.1 A o /s 、0.5–5 A o/s ,器件的有效面积为4mm 2。
OLED 器件的电学特性由电子仪器测量得到,光学特性通过使用皮安计测量OLED 器件光发射引起的光电流来得到。
图2所示为ITO 经过He(10 slm)/O 2(3 slm) 和 He(10 slm)/SF 6(100 sccm)常压等离子混合气体处理的OLED 器件的特性,例如:(a )亮度与电压的关系、(b )亮度与电流密度的关系、(c )功率效率与电流密度的关系。
作为参考,图中还包括了没经过等离子处理的OLED 器件的特性。
如图2(a )所示,经过等离子体He(10 slm)/O 2(3 slm) 和 He(10 slm)/SF 6(100 sccm)处理后的器件的开启电压(定义为发出1 cd/m 2的亮度所需的电压)分别为3.6V 和3.2V ,然而未经等离子体处理的器件的开启电压为4.2V 。
因此,经过等离子体处理后开启电压减小了,而且经He(10 slm)/O 2(3 slm)处理后的器件的开启电压比经He(10 slm)/SF 6(100 sccm)处理后的电压低。
此外,如图2(b )所示,在同一发光强度的条件下,经He(10 slm)/SF 6(100 sccm)处理的OLED 表现出了最低的电流密度,而没经处理的OLED 器件表现出了最高的电流密度。
通过对电流密度的测量,得到了用三种方法He(10 slm)/SF 6(100 sccm)、He(10 slm)/O 2(3 slm)和未做处理的三个器件的最高功率效率分别为0.93 Lm/W 、0.75 Lm/W 和0.58Lm/W 。
因此,经过He(10 slm)/SF 6(100 sccm)处理的OLED 器件显示了最佳的电学性能。
经过He(10 slm)/SF6(100 sccm)处理的OLED器件的电特性的改善看上去与去除ITO表面的有机杂质和经处理的ITO工作性能的改变有关。
表1显示了通过XPS测量的未经处理、He(10 slm)/O2(3 slm)和He(10 slm)/SF6(100 sccm)三种处理方法后的ITO表面的组成。
表中显示,经等离子处理后,ITO表面碳元素的含量显著的减少,而且,经He(10 slm)/SF6(100 sccm)处理后的ITO表面碳含量最少,因此,有机清洗后残留的有机杂质被等离子体清除了很多,有机杂质的去除被认为改善了OLED的性能。
当比较用He(10slm)/O2(3 slm) 和He(10slm)/SF6(100 sccm)处理的ITO表面组成时发现,在用He(10 slm)/SF6(100 sccm)清洁的ITO表面的氧被12%的氟代替,然而却没有发现硫元素。
ITO中氟的掺杂提高了ITO的电学特性,从而推理出氧化锡中掺杂氟可以提高空穴的注入效率。
此外,X射线电子谱线数据显示,即使在等离子处理后,锡铟比值没有显著变化,而表面Sn4+的含量却明显减少。
Sn3d5/2在峰值处可以分解成Sn2+和Sn4+的氧化物。
图3显示了将Sn3d5/2的峰值分解成Sn2+和Sn4+的XPS窄扫描数据。
如图所示,经过等离子体处理后的Sn4+的最高值有所减小,在经He(10 slm)/SF6(100 sccm)处理后为最低的峰值。
据报道,通过用In3+代替Sn4+的位置来减少Sn4+的含量,Sn4+的减少使n型的费米能级向中间能带改变,从而提高了ITO的工作性能。
因此,经用He(10 slm)/SF6(100 sccm)处理的OLED器件的改善也与增加氟元素和减少ITO表面Sn4+的含量来除去碳杂质以提高工作性能有关。
结论,利用常压等离子体设备使He(10 slm)/O2(3 slm) 和 He(10 slm)/SF6(100 sccm)的混合气体来处理ITO玻璃的表面以及它对ITO表面特性和ITO经过处理的OLED器件的特性的影响已经得到了研究。
经过He (10 slm)/SF6(100 sccm)处理的OLED器件拥有最好的电学特性,例如:最低的开启电压(在亮度均为1cd/m2的前提下,He/SF6处理后为3.2V,He/O2处理后为3.6V,未处理的为4.2V)、最高的亮度(在相同的电流密度下)和最高的功率效率(He/SF6处理后为0.93Lm/W,He/O2处理后为0.75Lm/W,未处理的为0.58Lm/W)。
He(10 slm)/SF6(100sccm)等离子体处理的OLED器件性能的改善与ITO表面有机杂质的去除、Sn4+的含量的降低以及ITO表面氟元素的掺杂有关,而且表明了ITO性能的提高。
因为常压等离子体不需要真空室,所以能够很容易安装负载室并应用于尺寸大于730mm*920mm的基板,常压等离子体可以成功的应用于商业制造OLED中ITO的清洗环节。
SF6低压等离子体处理和常压等离子体处理对ITO的影响正在进一步观察中。
这个课题得到了商务部、工业和能源部以及韩国科技部的国家研究实验室计划(海军研究实验所)的支持。
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Mater. 10 (1998) 859.Characteristics of Organic Light-Emitting Devices by the Surface Treatment of Indium Tin Oxide Surfaces Using Atmospheric PressurePlasmasChang Hyun JEONG, June Hee LEE, Y ong Hyuk LEE, Nam Gil CHO, Jong Tae LIM,Cheol Hee MOON and Geun Young YOMEDepartment of Materials Science & Engineering, Sungkyunkwan University, Suwon, 440-746, Korea PDP Division, Samsung SDI Co., Ltd., Cheonan, 330-300, Korea(Received October 4, 2004; accepted October 28, 2004; published December 10, 2004)ABSTRACT:This study examined the effects of a He/O2 and He/SF6 atmospheric pressure plasma surface treatment of indium tin oxide(ITO) glass on the ITO surface and electrical characteristics of organic light emitting diodes (OLEDs). The OLEDs composedof ITO glass/2-TNATA/NPD/Alq3/LiF/Al showed better electrical characteristics, such as lower turn-on voltage, higher power efficiency, etc., after the He/O2or He/SF6 plasma treatment. The He/SF6 treatment resulted in superior electrical characteristics compared with the He/O2 treatment. The electrical improvement as a result of the He/SF6 and He/O2 plasma treatments is related to the decrease in the carbon and Sn4t concentration on the ITO surface and fluorine doping of the ITO possibly indicating a change in the work function as a result of the treatments. [DOI: 10.1143/ KEYWORDS:ITO, surface treatment, atmospheric pressure plasma, OLED, He/O2, He/SF6 Organic light emitting diode (OLED) displays have been extensively studied due to their superior properties such as faster response time, lower operating voltage, higher quantum efficiency, etc. in addition to the simpler deposition processing and lower manufacturing cost compared with other flat panel displays such as liquid crystal displays and plasma display panels.1–3) Currently, these devices are manufactured in a high vacuum chamber for substrate areas smaller than 370mm×470mm using a multilayer evaporation technique for monomer organics, and deposition techniques for the large area substrates close to 920mm×730mm are currently under development. In addition, OLED displays utilizing polymer organics, which use inkjet printing instead of vacuum evaporation, are actively being studied.4,5)On OLED devices, a transparent conductor is used for the higher optical transparency, and among the various transparent conductors, indium tin oxide (ITO) is the most widely used due to its high conductivity and transparency. In order to form OLED devices, the organic monomers are deposited on patterned ITO glass for the formation of a low resistive ohmic contact. The contact resistance between the ITO and organic materials of the OLED devices can be altered by the ITO surface preparation due to the organic materials on the ITO glass surface and the change in the ITO composition as a result of the ITO surface preparation method. ITO is a nonstoichiometric compound. Therefore, the chemical composition can be easily changed.6) Consequently, in order to improve the contact properties between the ITO and the organic material of the OLED, the surface treatment of the patterned ITO before depositing the organic materials is very important.6–13) As surface treatment methods, low pressure plasma techniques,6–10,12) UV/O3 techniques,9–11) and wet treatments12,13)have been used to remove the organic materials and improve the ITO surface properties. However, these techniques are expensive and difficult to scale to large areas using low pressure plasma and UV/O3 techniques. In addition, there are environmental issues in the case of wet treatment.Atmospheric pressure plasma such as a corona discharge,14)dielectric barrier discharge (DBD),15,16) atmospheric plasma jet,17) etc. for the treatment of various surfaces applied to electric materials, electronic materials, biomaterials, structural materials, etc. have been actively studied in order to replace low pressure plasma techniques, wet processing, etc. This study examined the potential of using atmospheric pressure plasma for the surface treatment and cleaning of ITO glass for OLED devices. As an atmospheric pressure plasma cleaning technique, a modified DBD, which can be scaled to large areas and show a higher plasma density than conventional DBD, was used. By varying the gas mixture in the modified DBD, the effects of the gas mixture on the characteristics of the ITO surface and on the electrical properties of the OLED devices formed on the cleaned ITO glass were investigated.Figure 1 shows a schematic diagram of the atmospheric pressure plasma equipment used in this study forthe surface treatment of ITO glass. As shown in the figure, the modified DBD used in this study was composed of a pyramid shaped multi-pin electrode as the power electrode instead of a plate electrode, a plate electrode as the ground electrode, and dielectric materials on both electrodes. Using the multi-pin electrode instead of a blank plate electrode, a higher plasma density and gas breakdown at a lower AC voltage could be obtained by forming a high electric field on the tip of the pins similar to the corona discharge with a higher stability and glow discharge shape instead of a filamentary discharge shape. The AC voltage in the range from 3 to 15 kV with a frequency of 20–30 kHz was connected to the multi-pin power electrode and the ground was connected to the plate ground electrode.Fig. 1. Schematic diagram of the atmospheric pressure plasma equipmentused for the surface treatment of ITOglass.He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) were used as the ITO surface cleaning gas mixtures for the OLED devices. Before the plasma treatment, all the ITO glasses were cleaned with an organic solvent. These optimum gas compositions were selected after measuring the contact angle by a contact angle measuring tool and the carbon contents on the ITO surface by X-ray photoelectron spectroscopy (XPS, VG Microtech Inc., ESCA2000) after varying the O2 flow rate from 0 to 3 slm and the SF6 flow rate from 0 to 500 sccm with a He flow rate of 10 slm. The AC voltage used was 10 kV at 25 kHz and the processing time was 30 seconds. The composition of the ITO surface after cleaning with the He/O2and He/SF6plasma was investigated by XPS using Al KX-ray source of 1486.6 eV.The OLED devices were fabricated on the cleaned ITO by the thermal evaporation of the OLED materials andelectrode materials sequentially without breaking the vacuum.The OLED structure used in this study was ITO glass/2-TNATA(60 nm)/NPD(20 nm)/Alq3(40 nm)/LiF(1 nm)/Al(100 nm). The deposition rates of the organic materials, LiF, and Al were 0.3–0.5Å /s, 0.1 Å /s, and 0.5–5 Å /s, respectively. The fabricated device active area was 4mm2. The electrical characteristics of the fabricated OLED devices were measured using an electrometer (Keithley 2400) and the luminescence characteristics were determined by measuring the photocurrent induced by light emission from the OLEDs using a picoammeter (Keithley 485).Figure 2 shows the characteristics of the OLEDs fabricated on the ITO glass cleaned by the atmospheric pressure plasma using the He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) gas mixtures such as (a) luminescencevoltage, (b) luminescence-current density, and (c) power efficiency-current density. As a reference, the characteristics of the OLED device fabricated without plasma cleaning were included. As shown in Fig. 2(a), the turn-on voltages of the devices (defined as the voltage required to deliver a luminescence of 1 cd/m2) after the He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) treatment were 3.6V and 3.2 V, respectively, while the turn-on voltage ofthe device without the plasma treatment was 4.2 V.Therefore, after the plasma treatment, the turn-onvoltage was decreased and the He(10 slm)/O2(3 slm)treatment showed a lower turn-on voltage than theHe(10 slm)/SF6(100 sccm) treatment. In addition, asshown in Fig. 2(b), the OLED treated by He(10slm)/SF6(100 sccm) showed the lowest currentdensity at the same emission intensity while theOLED fabricated without the plasma treatment showed the highest current density. When the power efficiency was measured as a function of the current density, the highest power efficiencies were ~0.93 Lm/W, ~0.75 Lm/W, and ~0.58 Lm/W for the He(10 slm)/SF6(100 sccm) treated sample, He(10 slm)/O2(3 slm) treated sample, and the non-treated sample, respectively. Therefore, after the He(10 slm)/SF6-(100 sccm) treatment, the device showed the best electrical performance.Fig. 2. Characteristics of the OLEDs fabricated on the ITO glass cleaned by the atmospheric pressure plasma using He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) gas mixtures. (a) luminescence-voltage, (b)luminescence-current density, and (c) power efficiency-current density.As a reference, the characteristics ofthe OLED device fabricated withoutplasma cleaning are included.The improved electrical characteristics shown for the OLED after the He(10 slm)/SF6(100 sccm) treatment appeared to be related to the removal of the remaining contaminants on the ITO surface and the change in the work function of the ITO as a result of the plasma treatment. Table I shows the composition of the non-treated (as is) and He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm) treated ITO surface measured by XPS. As shown in the table, carbon contamination on the surface decreased significantly as a result of the plasma treatment and the ITO surface after the He(10 slm)/SF6(100 sccm) treatment showed the lowest carbon content on the surface. Therefore, the organic contaminants remaining after organic cleaning were removed further after the plasma cleaning, and the removal of the organic contaminants is believed to be partially responsible for the improved OLED performance.Table I. Composition of the ITO surfaces not treated (as is) and treated with He(10 slm)/O2(3 slm) and He(10slm)/SF6(100 sccm) measured by XPS.In the case of the He(10 slm)/SF6(100 sccm) cleaning, 12% of fluorine (F1s 685 eV) was detected on the ITO surface, which replaced oxygen on the surface when comparing the surface compositions of the ITO cleaned by the He(10 slm)/O2(3 slm) and that by the He(10 slm)/ SF6(100 sccm). However, sulfur (S2p 164 eV) was not detected on the ITO surface as a result of the He(10 slm)/ SF6(100 sccm) treatment. The doping of fluorine on the ITO is known to improve the electrical properties of ITO similar to the doping of fluorine on SnO2 by increasing the level of hole injection to the device.8,19) In addition, in the XPS data, even though the Sn to In ratio was not significantly altered by the plasma treatment, the surface concentration of Sn4+was deceased significantly by the plasma treatment. The Sn3d5/2 peak can be deconvoluted into the: Sn2+(486.3 eV) and Sn4+ (487.3 eV) oxidation states7) and Fig. 3 shows the narrow scan XPS data of the deconvoluted Sn2+ and Sn4+ peaks of Sn3d5/2 peak are shown in. As shown in the figure, the Sn4+ peak intensity was deceased by the plasma treatment and showed the lowest peak for the He(10 slm)/ SF6(100 sccm) treatment. It was reported that the substitution of an In3+site by Sn4+ decreases the Sn4+ content and the decrease in Sn4+increases the work function of ITO by changing the n-type Fermi level toward the middle of the band gap.18) Therefore, the improvement in the OLED devices treated with the He(10 slm)/SF6(100 sccm) is also related to the increase in the work function by the fluorination and the decrease in the Sn4+level of the ITO in addition to the removal of carbon contaminants on the ITO surface.Fig. 3. Narrow scan XPS data of the deconvoluted Sn2+ and Sn4+ peaksfrom the Sn3d5/2 peaks of the ITO surface treated with He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100 sccm). The XPS data of the ITO surfacenot treated by the plasma is also included.In conclusion, the ITO glass surfaces were treated with He(10 slm)/O2(3 slm) and He(10 slm)/SF6(100sccm) gas mixtures using an atmospheric pressure plasma equipment composed of a multi-pin type DBD and its effects on ITO surface properties and the characteristics of the OLED devices fabricated on the treated ITO were investigated. The OLED devices treated with the He(10 slm)/SF6(100 sccm) plasma showed the best electrical properties such as the lowest turn-on voltage (He/SF6plasma treatment: 3.2 V, He/O2plasma treatment: 3.6V, non-treatment: 4.2V at the luminescence of 1 cd/m2), highest luminescence at the same current density, and the highest power efficiency (He/SF6plasma treatment: 0.93 Lm/W, He/O2plasma treatment: 0.75 Lm/W, non-treatment: 0.58 Lm/W). The improved properties of the OLED devices after the ITO treatment using He(10 slm)/SF6(100 sccm) appear to be related to the removal of the organic contaminants remaining on the ITO surface, the decrease in the Sn4+ level, and the fluorine doping on the ITO surface possibly indicating an increase in the work function of the ITO. Because atmospheric pressure plasma does not require a vacuum chamber, it can be installed easily in the loading chamber, and be scaled to substrates larger than 730mm×920mm in size. It is believed that the use of He(10 slm)/SF6(100 sccm) atmospheric pressure plasma can be successfully applied to a commercial OLED system requiring ITO cleaning. 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