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

B Rackauskas,M.J Uren,T Kachi,M Kuball

doi:10.1016/j.microrel.2019.02.013

B Rackauskas, M.J Uren + Show 2 more

Open Access

https://doi.org/10.1016/j.microrel.2019.02.013

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Abstract

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 μm diameter diode.

Highlights

Power electronic systems have begun to adopt GaN based power devices in recent years based on their ability to operate at high power with high efficiency
Recent developments in the growth of bulk GaN has led to a drop in the cost of substrates and GaN-on-GaN devices have become more economically viable
The currents during the step stress measurement of the twelve small devices are shown in Fig. 2, with the stress condition shown on the right axis

Summary

Introduction

Power electronic systems have begun to adopt GaN based power devices in recent years based on their ability to operate at high power with high efficiency. These lateral devices are replacing their Si equivalents due to the superior material properties of GaN, the high breakdown field and high 2DEG mobility [1]. Some groups have reported avalanche breakdown indicating suppression of defect related breakdown [5,6,7] Despite this progress, there are only a few published reliability studies on these devices [8,9,10,11] and no lifetime estimations. The failure of AlGaN/GaN HEMTs has been shown to follow the same failure distributions indicating a similar failure mechanism occurs in GaN [13]

Results

Discussion

Conclusion