On the origin of the leakage current in p-gate AlGaN/GaN HEMTs

TitleOn the origin of the leakage current in p-gate AlGaN/GaN HEMTs
Publication TypeConference Paper
Year of Publication2018
AuthorsStockman A., Canato E., Tajalli A., Meneghini M., Meneghesso G., Zanoni E., Moens P., Bakeroot B.
Conference Name2018 IEEE International Reliability Physics Symposium (IRPS)
Date PublishedMarch
KeywordsAlGaN-GaN, aluminium compounds, Aluminum gallium nitride, charge injection, double pulse measurement, double pulse measurements, double pulsed testing, electron injection, electron traps, enhancement mode power transistor, gallium compounds, GaN, gate leakage current, HEMT, HEMTs, high electron mobility transistors, high-electron-mobility transistor, hole trap, hole traps, III-V semiconductors, interface quality, interface states, leakage current, leakage currents, Logic gates, MODFETs, ositive threshold voltage shift, p-GaN gate, passivation, power transistors, Schottky barriers, Schottky metal-semiconductor interface quality, semiconductor device breakdown, semiconductor-metal boundaries, sidewall leakage, sidewall passivation, sidewall roughness, temperature dependent DC neasurement, Temperature measurement, wide band gap semiconductors

Temperature dependent DC and double pulse measurements are performed on p-GaN gated AlGaN/GaN enhancement mode power transistors. Devices with improved Schottky metal/p-GaN interface quality and p-GaN sidewall passivation are studied. It is shown that both processes reduce the reverse and forward gate leakage current significantly. This is related to the improved p-GaN sidewall roughness and density of interface states, all contributing to sidewall leakage. Under double pulsed testing, an untreated device shows a negative threshold voltage shift at high forward gate voltage, which is explained by hole trapping in the barrier. Improving the p-GaN sidewall quality reduces the supply of holes towards the p-GaN/AlGaN interface, and a positive threshold voltage shift is observed. This can be explained by electron injection from the channel into the barrier.