Study of Avalanche Behavior in 3 kV GaN Vertical P-N Diode Under UIS Stress for Edge-termination Optimization

This work investigates both avalanche behavior and failure mechanism of 3 kV GaN-on-GaN vertical P-N diodes, that were fabricated and later tested under unclamped inductive switching (UIS) stress. The goal of this study is to use the particular avalanche characteristics and the failure mechanism to identify issues with the field termination and then provide feedback to improve the device design. DC breakdown is measured at the different temperatures to confirm the avalanche breakdown. Diode’s avalanche robustness is measured on-wafer using a UIS test set-up which was integrated with a wafer chuck and CCD camera. Post failure analysis of the diode is done using SEM and optical microscopy to gain insight into the device failure physics.