Investigation of trapping/de-trapping dynamics of surface states in AlGaN/GaN high-electron mobility transistors based on dual-gate structures

Abstract

The mechanism of current collapse in AlGaN/GaN high-electron-mobility transistors (HEMTs) passivated with low-pressure chemical vapor deposited (LPCVD)-SiNx layers, is revealed by a double-sweep current-voltage measurement of a dual-gate HEMT structure. It provides an in-situ observation of the trapping/de-trapping process of surface states in HEMTs under high-voltage switching stress, by examining the gate-to-gate surface-hopping leakage IS along with several critical features, such as sweeping-rate and voltage-dependent onset voltage, turn-on slope, onset voltage hysteresis, and current tailing, etc. It is also verified that the plasma-enhanced atomic layer deposited (PEALD) 3-nm -SiNx interfacial layer inserted between the LPCVD-SiNx passivation and the AlGaN barrier, is beneficial for suppressing the surface-trap-induced current collapse in AlGaN/GaN HEMTs.