Influence of annealing on electrical properties of AlGaN/GaN HFETs and MOSHFETs using Al2O3

Thermal annealing was used to investigate traps at the surface of AlGaN/GaN HFETs and Al2O3/AlGaN/GaN MOSHFETs. The C-V and static output and transfer measurement yielded nearly identical characteristics for unannealed and annealed structures, regardless whether unpassivated or gate-oxide structures were used A strong influence of the annealing on the gate leakage current was observed. The leakage currents were lowered by about two orders of magnitude, which is indicative of an efficient reduction of traps in the AlGaN/GaN heterostructure because of annealing.