Optimizing breakdown voltage and on-state resistance by modulating the barrier height along 2DEG channel for power p-GaN HEMTs

Abstract

This article proposes a novel step-type gate p-GaN HEMT (STG-HEMT) to optimize breakdown voltage (BV) and on-state resistance (R ON) by modulating the barrier height along the two-dimensional electron gas (2DEG) channel. The step-type gate consists of thicker and thinner p-GaN layers. At off-state, the barrier height is higher due to the clamping potential effect induced by the thinner p-GaN layer, which contributes to improving BV. At on-state, the barrier height under the thinner p-GaN layer is lower, which contributes to improving 2DEG density under the gate (namely reducing R ON). Verified by the calibrated simulation, the results show STG-HEMT’s BV is increased by 55% and STG-HEMT’s R ON is decreased by 20% compared with the conventional power p-GaN HEMT (C-HEMT). At transient behavior, the total switching loss keeps nearly unchanged, while the gate driver loss is increased by about 19%. Furthermore, the impact of the gate length and p-GaN layer’s parameters (including thickness, length, activated Mg doping density) on R ON, BV, and threshold voltage are discussed.