High Voltage Vertical p-n Diodes with Ion-Implanted Edge Termination and Sputtered SiNx Passivation on GaN substrates

High-voltage vertical GaN-on-GaN power diodes with partially compensated ion-implanted edge termination (ET) and sputtered SiNx passivation are reported. The measured devices exhibit a breakdown voltage (V-br) exceeding 1.2 kV. Optimization of the ion-implantation-based ET has been performed through simulation and experiment, and the impact of SiNx surface passivation on breakdown has also been evaluated. Use of a partially-compensated ET layer, with approximately 40 nm of the p-type anode layer remaining uncompensated by the implant, is optimal for maximizing Vbr. Additionally, sputter-deposited SiNx, rather than the more conventional plasma-enhanced chemical vapor deposition (PECVD)-based SiNx, results in less degradation in the on-state performance while providing the same V-br. The diodes support current densities of 8 kA/cm(2) at a forward voltage 5 V, with differential specific on resistances (R-on) of 0.11 m Omega cm(2). A Baliga's figure-of merit (BFOM) of 13.5 GW/cm(2) is obtained; this is among the highest reported BFOM for GaN homoepitaxial pn diodes.