Gate Stability and Robustness of In-Situ Oxide GaN Interlayer Based Vertical Trench MOSFETs (OG-FETs).

Vertical GaN devices are currently studied for application in next-generation power converters, but very little is known about their reliability. This work presents the first analysis on the stability of In-Situ Oxide GaN Interlayer based Vertical Trench MOSFET (OG-FET) submitted to forward gate bias. Based on pulsed measurements, step stress tests and threshold voltage transients we demonstrate the following original results: (i) under forward gate bias, the devices show a good stability up to 6-7 V; (ii) higher stress voltages induce a positive shift of threshold voltage (V TH ), which has a logarithmic time-dependence and is ascribed to the injection of electrons in the oxide. (iii) The trapping mechanisms are recoverable; the related kinetics were investigated by means of threshold voltage transients at different temperatures.