High voltage, high current GaN-on-GaN p-n diodes with partially compensated edge termination

Abstract

An approach to realizing high-voltage, high-current vertical GaN-on-GaN power diodes is reported. We show that by combining a partially compensated ion-implanted edge termination (ET) with sputtered SiNx passivation and optimized ohmic contacts, devices approaching the fundamental material limits of GaN can be achieved. Devices with breakdown voltages (Vbr) of 1.68 kV and differential specific on resistances (Ron) of 0.15 mΩ cm2, corresponding to a Baliga figure of merit of 18.8 GW/cm2, are demonstrated experimentally. The ion-implantation-based ET has been analyzed through numerical simulation and validated by experiment. The use of a partially compensated ET layer, with approximately 40 nm of the p-type anode layer remaining uncompensated by the implant, is found to be optimal for maximizing Vbr. The implant-based ET enhances the breakdown voltage without compromising the forward characteristics. Devices exhibit near-ideal scaling with area, enabling currents as high as 12 A for a 1 mm diameter device.