Imaging of the Schottky Barriers and Charge Depletion in Carbon Nanotube Transistors
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- 作者：Marcus Freitag ; James C. Tsang ; Ageeth Bol ; Dongning Yuan ; Jie Liu ; Phaedon Avouris
- 刊名：Nano Letters
- 出版年：2007
- 出版时间：July 2007
- 年：2007
- 卷：7
- 期：7
- 页码：2037 - 2042
- 全文大小：274K
- 年卷期：v.7,no.7(July 2007)
- ISSN：1530-6992
文摘
The photovoltage produced by local illumination at the Schottky contacts of carbon nanotube field-effect transistors varies substantially withgate voltage. This is particularly pronounced in ambipolar nanotube transistors where the photovoltage switches sign as the device changesfrom p-type to n-type. The detailed transition through the insulating state can be recorded by mapping the open-circuit photovoltage as afunction of excitation position. These photovoltage images show that the band-bending length can grow to many microns when the device isdepleted. In our palladium-contacted devices, the Schottky barrier for electrons is much higher than that for holes, explaining the higherp-type current in the transistor. The depletion width is 1.5 
m near the n-type threshold and smaller than our resolution of 400 nm near thep-type threshold. Internal photoemission from the metal contact to the carbon nanotube and thermally assisted tunneling through the Schottkybarrier are observed in addition to the photocurrent that is generated inside the carbon nanotube.
m near the n-type threshold and smaller than our resolution of 400 nm near thep-type threshold. Internal photoemission from the metal contact to the carbon nanotube and thermally assisted tunneling through the Schottkybarrier are observed in addition to the photocurrent that is generated inside the carbon nanotube.