Temperature dependence and current transport mechanisms in AlxGa1−xN Schottky rectifiers

GaN and Al0.25Ga0.75N lateral Schottky rectifiers were fabricated either with (GaN) or without (AlGaN) edge termination. The reverse breakdown voltage VB (3.1 kV for GaN; 4.3 kV for AlGaN) displayed a negative temperature coefficient of −6.0±0.4 V K−1 for both types of rectifiers. The reverse current originated from contact periphery leakage at moderate bias, while the forward turn-on voltage at a current density of 100 A cm−2 was ∼5 V for GaN and ∼7.5 V for AlGaN. The on-state resistances, RON, were 50 mΩ cm2 for GaN and 75 mΩ cm2 for AlGaN, producing figures-of-merit (VRB)2/RON of 192 and 246 MW cm−2, respectively. The activation energy of the reverse leakage was 0.13 eV at moderate bias.