Method of evaluating interface traps in Al2O3/AlGaN/GaN high electron mobility transistors**Project supported by the Key Program of National Natural Science Foundation of China (Grant Nos. 61334002 and 61634005) and the National Natural Science Foundation of China (Grant Nos. 61604114 and 61704124).

Abstract

In this paper, the interface states of the AlGaN/GaN metal–insulator–semiconductor (MIS) high electron mobility transistors (HEMTs) with an Al2O3 gate dielectric are systematically evaluated. By frequency-dependent capacitance and conductance measurements, trap density and time constant at Al2O3/AlGaN and AlGaN/GaN interface are determined. The experimental results reveal that the density of trap states and the activation energy at the Al2O3/AlGaN interface are much higher than at the AlGaN/GaN interface. The photo-assisted capacitance-voltage measurements are performed to characterize the deep-level traps located near mid-gap at the Al2O3/AlGaN interface, which indicates that a density of deep-level traps is lower than the density of the shallow-level states.