Numerical analysis of high‐voltage RESURF AlGaN/GaN high‐electron‐mobility transistor with graded doping buffer and slant back electrode

Abstract

A reduced surface field (RESURF) AlGaN/GaN high-electron-mobility transistor (HEMT) with graded doping buffer (GDB) and slant back electrode (SBE) is proposed. In the GDB, the p-dopant density increases linearly both from top to bottom and right to left. The concentrated negative space charges in the lower-left corner of GDB attract the electric field lines from the channel and barrier towards the gate under OFF-state, which flats the electric field and enhances the breakdown voltage (V br). Additionally, the low p-dopant density near the top of GDB achieves the device with low ON-state resistance (R ON). The SBE flats the electric field along the channel above it and introduces a peak electric field near its edge. Simulation results show a V br of 2150 V and R ON of 7.05 Ωmm for the proposed device, compared with 1701 V and 7.73 Ωmm for the conventional back electrode RESURF HEMT (BE-RESURF HEMT) with the same gate-drain spacing. Moreover, due to the reduced depletion of 2DEG from the GDB, the proposed device shows slight increases in f T and f max (8.76 and 14.80 GHz), comparing with the conventional BE-RESURF HEMT (8.24 and 13.84 GHz).