Reliability and lifetime estimations of GaN-on-GaN vertical pn diodes

This work presents the first lifetime estimation of vertical GaN-on-GaN pn diodes using a step stress measurement technique with analysis not previously applied to GaN. The failure mechanism is surface breakdown, indicating that the lifetime is not yet limited by intrinsic material properties but by device design. As such, the mean time to failure depends on the peripheral length of the device. An estimated operating MTTF of 10 years at a reverse bias stress of 260 V was calculated for a 126 mu m diameter diode.