Low Frequency Noise in Carbon Nanotube Field Effect Transistors

It is critical to understand the noise performance of the carbon nanotube field effect transistors (CNT-FETs) due to their ultra-small diameters and large surface to volume ratios. In the abstract, we will describe the noise study of an ambipolar CNT-FET with a negative threshold of 5V and a positive threshold of 15V. The noise power spectra densities (PSDs) are obtained for frequencies from 0.0625Hz to 10.24kHz, showing 1/f$^{\alpha }$ behavior. The exponential $\alpha $ of this 1/f$^{\alpha }$ increases from about 0.6 to 1.2 for a gate bias from -6V to -15V at a small source-drain bias (-0.1V) and this exponential gate bias dependence comes from schottky contacts, where shot noise is the dominant noise component. We also observe a greater excess 1/f noise for electron conducting than that for hole conducting, suggesting higher defect density near the CNT conduction band. The characteristics of the CNT-FET noise are different from conventional MOSFET, and thus, additional studies are needed to understanding the noise in CNT-FETs.