Reliability investigation of AlGaN/GaN high electron mobility transistors under reverse-bias stress

Abstract

Impact of reverse-bias stress on the reliability of AlGaN/GaN high electron mobility transistors was investigated in this paper. We found that inverse piezoelectric effect could induce noisy characteristics of stress current, and the “critical voltage” increased with the drain–source bias in the step-stress experiments. Although the degradation of the gate leakage current and drain-to-source leakage current are non-recoverable, the maximum output current can recover almost completely through electron de-trapping procedure after stress. The de-trapping activation energy was estimated to be 0.30eV by the dynamic conductance technique. The surface morphology of the electrically stressed devices was investigated after removing the gate metallization by chemical etching, and no pits or cracks under the gate contact were observed.