Low Turn-on Voltage Fully Vertical GaN-on-SiC PiN Diodes achieved by Recovering GaN Surface

Abstract

This work reports the achievement of a low turn-on voltage fully vertical GaN-on-SiC PiN diode by recovering GaN surface. The surface recovery approach is highly compatible with the existing fabrication process of GaN/SiC hybrid devices. This approach involves reduction and recovery of nitrogen vacancies on GaN surface, realizing directly by the high-temperature annealing for the formation of SiC Ohmic contact in NH3/N2 atmosphere. Transmission Line Model measurements indicate that the current after GaN surface recovery demonstrates improved Ohmic characteristics, closely resembling that of an undamaged state. By implementing this annealing process, the turn-on voltage of fully vertical GaN-on-SiC PiN diodes is reduced to 2.7V.