Surface Potential Measurement of Carbon Nanotube Field-Effect Transistors Using Kelvin Probe Force Microscopy

The surface potential of carbon nanotube field-effect transistors (CNT-FETs) was measured using Kelvin probe force microscopy (KFM). A clear potential image of the CNT channel with a diameter of 1.1 nm was obtained by measurement in air. The measured potential image was dependent on the sequence of the gate bias, and showed transient behavior with a time constant of several tens of minutes. These behaviors were consistent with the drain current transient and the hysteresis of the current–voltage characteristic of the CNT-FETs.