Vertical gallium nitride high-temperature avalanche pin diodes with guard rings structure

Abstract The avalanche capability is essential for high-reliability power electronics devices, but it is difficult to realize avalanche breakdown, which requires high-quality freestanding GaN substrates and sophisticatedly designed edge termination. In this study, the avalanche characteristics of vertical GaN PIN diodes with N-ion implantation guard rings (GRs) were investigated. GaN p–i–n diodes were grown on freestanding GaN substrates by metal–organic chemical vapor deposition. The net carrier concentration in the drift layer is as low as 3.5 × 10 15 cm −3 measured by capacitance–voltage ( C – V ) test. The GRs was formed on the edge of p–i–n diodes via N-ion implantation, resulting in a significant reduction in reverse leakage current density by over 10 6 times. By optimization of the GRs through a combination of simulations and experiments, we achieved an enhancement in the device’s avalanche breakdown voltage from 759.8 V to 865 V. Notably, the devices maintained an avalanche damage-free breakdown even at an elevated temperature of 225 °C. The relationship between avalanche voltage and temperature is linear, with a positive temperature coefficient of 0.38 V K −1 .