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Silicon Metal-oxide-semiconductor Quantum Dots for Single-electron Pumping
Published on: June 3, 2015
Ballistic carbon nanotube field-effect transistors
Ali Javey1, Jing Guo, Qian Wang
1Department of Chemistry, Stanford University, California 94305, USA.
Nature
|August 9, 2003
Summary
Researchers minimized Schottky barriers in single-walled carbon nanotube field-effect transistors using palladium contacts. This breakthrough enables near-ballistic transport and high current capabilities for advanced electronic devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Schottky barriers at nanotube-metal junctions limit single-walled carbon nanotube field-effect transistor (SWCNT-FET) performance.
- These barriers reduce ON-state conductance and current delivery capability, hindering device applications.
Purpose of the Study:
- To investigate palladium (Pd) as a contact material for SWCNTs.
- To reduce or eliminate Schottky barriers in SWCNT-FETs.
- To understand the role of electrode work function in contact properties.
Main Methods:
- Fabrication of SWCNT-FETs using palladium electrodes.
- In situ modification of electrode work function with hydrogen.
- Electrical characterization of transistor performance, including ON-state conductance and current-carrying capability.
- Low-temperature measurements to observe quantum phenomena like Fabry-Perot interferences.
Main Results:
- Palladium contacts significantly reduce or eliminate Schottky barriers for valence band transport in semiconducting SWCNTs.
- Achieved room-temperature conductance near the ballistic limit (4e(2)/h).
- Demonstrated high current-carrying capability (approx. 25 micro A/tube) and observed Fabry-Perot interferences.
Conclusions:
- High-performance ballistic SWCNT-FETs with negligible Schottky barriers are realized using palladium contacts.
- Current saturation under high voltage is attributed to optical phonon backscattering.
- Pd contacts enable SWCNT-FETs to approach ideal ohmic contact behavior.
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