Gate Stability of GaN-Based HEMTs with P-Type Gate

This paper reports on an extensive investigation of the gate stability of GaN-based High Electron Mobility Transistors with p-type gate submitted to forward gate stress. Based on combined electrical and electroluminescence measurements, we demonstrate the following results: (i) the catastrophic breakdown voltage of the gate diode is higher than 11 V at room temperature; (ii) in a step-stress experiment, the devices show a stable behavior up to V-GS = 10 V, and a catastrophic failure happened for higher voltages; (iii) failure consists in the creation of shunt paths under the gate, of which the position can be identified by electroluminescence (EL) measurements; (iv) the EL spectra emitted by the devices consists of a broad emission band, centered around 500-550 nm, related to the yellow-luminescence of GaN; and (v) when submitted to a constant voltage stress tests, the p-GaN gate can show a time-dependent failure, and the time to failure follows a Weibull distribution.