Breakdown voltage enhancement of p-GaN/AlGaN/GaN diode by controlling Mg acceptors for compensating residual Si donors

Abstract

Breakdown voltage enhancement was studied for p-GaN/AlGaN/GaN heterostructure diodes, where residual Si donors during growth were compensated with Mg acceptors doped in the p-GaN layer. As the thicknesses of the p-GaN layer (T p-GaN) decreased from 140 nm, breakdown voltages were increased and maximized at 20 nm, then decreased at 0 nm. Moreover, breakdown voltages of the 20 nm T p-GaN diodes improved with the increase of the drift region lengths. This is because a uniform electric field was obtained by compensation of the residual Si donors with the Mg acceptors. In addition, for a thicker p-GaN layer, the effects of the surface states were suppressed, and injection of a large number of holes under forward bias was observed. Consequently, the thick p-GaN layer is expected to enhance forward current. Adopting the results, the potential of low on-resistance and high current for p-GaN gated anode diodes was demonstrated.