Electrical Properties of Al/CaF₂/i-Diamond Metal-Insulator-Semiconductor Field-Effect-Transistor Fabricated by Ultrahigh Vacuum Process

Abstract

In order to avoid oxygen contamination on the diamond surface as far as possible during the device process, the diamond metal-insulator-semiconductor field-effect transistor (MISFET) was prepared by a reduced-oxygen process including an ultrahigh vacuum (UHV) process for the first time, and its electrical properties were investigated in detail. According to the results, it was found that the electrical properties of the MISFET were improved to a great extent in comparison with those of conventional diamond MISFETs. The observed effective mobility (µ eff ) was 400 cm 2 /V·s at room temperature, which is the highest value obtained until now in the diamond FET at room temperature. Besides, the measured transconductance ( g m ) and surface state density ( N SS ) of the device operation region was 5 mS/mm and ∼10 10 /cm 2 ·eV, respectively, which is also comparable with conventional Si metal-oxide-semiconductor field-effect-transistors (MOSFETs) with the same gate length ( L g = 30 µm).