Thermal instability of copper gate AlGaN/GaN HEMT on Si substrate

Thermal reliability of nickel (Ni) and copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) is investigated. Though the current-voltage characteristics of as-deposited Cu gate AlGaN/GaN HEMTs is superior to those of Ni gate AlGaN/GaN HEMTs, severe degradation was observed after aging at 220°C. This instability problem should be carefully taken into account in practical applications of Cu gate AlGaN/GaN HEMTs.