Low turn-on voltage fully vertical GaN-on-SiC PiN diodes achieved by recovering GaN surface

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 NH 3 /N 2 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 2.7 V. • A method enables simultaneous SiC ohmic contact formation and GaN surface restoration. • This annealing approach is compatible with the Ohmic contact process of both GaN and SiC. • Restored GaN surfaces exhibit Ohmic characteristics approaching pristine-state performance. • The V on of GaN/SiC vertical PiN diodes achieve 2.7 V, matching homoepitaxial GaN devices.