s-SWNT自生长整齐排列半导体性碳纳米管分析——北京大学PKU

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Carbon Nanotubes
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Brief Introduction
What is the Carbon nanotubes(CNTs)?
allotropes of carbon with a cylindrical nanostructure. The atomic structure can be formed by wrapping a stripe of single layer of carbon atoms along a certain direction. This direction determines the diameter and chirality of the nanotubes.
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CaNew Progress
Build field effect transistor(FET) devices
exploited the high quality, purity, relatively large diameter, high packing density and good alignment of s-SWNTs.
Integration of the sorted s-SWNTs
s-SWNTs could be self aligned into raft assemblies by utilizing depletion attraction forces originated from entropic effects at high surfactant loading.
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Standford‟s New Progress
Build field effect transistor(FET) devices
highest current achieved by the semiconducting raft FET devices on 10nm SiO2 was 121μA under a 1V bias. on/off ratio of this device was ∼4000 under a 1V bias. The number of SWNTs was ∼37,corresponding to an average of 3.2μA /SWNT. highest current density achieved was 160μA/μm in a different device with a raft width of ∼500 nm.
Challenges
The production of pure semiconducting SWCNTs. Integration into ordered structures.
How did they face the challenges?
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Surfactant loading
sodium cholate (SC) and sodium dodecyl sulfate (SDS) solutions. a process driven by depletion attraction during water evaoration on a (3-aminopropyl) triethoxysilane (APTES)-modified SiO2 /Si substrate. Surfactants act: depletion agents in solution and surface ligands to stabilize SWNT suspension.
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Standford‟s New Progress
The result after separation
We get highly pure s-SWNTs.
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Standford‟s New Progress
Advantage of CNTs
extraordinary thermal conductivity and mechanical and electrical properties
Classifications
single-walled carbon nanotubes (SWNTs) multi-walled carbon nanotubes (MWNTs).
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Standford‟s New Progress
Key Words
Self-Assembly. Semiconducting Single-Walled Carbon Nanotubes(s-SWNTs). Dense, Aligned rafts.
CNRI: Corporation for National Research Initiatives.
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Brief Introduction
History of CNTs In 2007, Japan develop the technology of directly syhthesising a large number of SWNTs, called “Super Growth”. In 2010, researchers coming from Zhejiang Uni.& Uni. of California synthesized fullerence C90, owing the world’s smallest CNT structure. In 2012, the application of CNT in biosensors make the speed of prototype biosensor almost tripled.
Band gap
Their band gap can vary from zero to about 2eV and their electrical conductivity can show metallic or semiconducting behavior.
Adventage
Single-walled nanotubes are likely candidates for miniaturizing electronics. One useful application of SWNTs is in the development of the first intermolecular field-effect transistors (FET).
Standford‟s New Progress
Challenges
The production of pure semiconducting s-SWNTs. Integration into ordered structures.
Standford’s New Progress
Self-Assembly of Semiconducting Single-walled Carbon Nanotubes
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Contents
1. Brief Introduction 2. Semiconducting Single-Walled Carbon Nanotubes(Semic-SWNTs) 3. Standford’s New Progress 4. Summary
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Standford‟s New Progress
Depletion force
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Standford‟s New Progress
AFM images of semiconducting SWNT rafts
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Semiconducting SWNTs
SWNTs are an important variety of carbon nanotube because
Most of their properties change significantly with the (n,m) values, and this dependence is non-monotonic. The integers n and m denote the number of unit vectors along two directions in the honeycomb crystal lattice of graphene.
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Standford‟s New Progress
Self-assembly
A unique „bottom-up‟ approach for making well-ordered architectures. Place SWNTs into patterned trenches with controlled trench density. But the inter-tube relations (density and align-ment) within a trench are not defined or controlled.
Standford‟s New Progress