Stable AlGaN/GaN high electron mobility transistors with tungsten nitride gate metallisation

An AlGaN/GaN high electron mobility transistor (HEMT) with tungsten nitride (WNx) Schottky gate fabricated on a sapphire substrate is presented. Gate forward current stress was chosen to evaluate the stability of the Schottky gate. After stress, this WNx HEMT remains stable, while the conventional Ni/Au HEMT shows performance degradation and failure. The maximum output power density from this device is 5 W/mm at 2 GHz. A combination of these findings indicates the robust performance of this WNx material and its potential as a Schottky gate for AlGaN/GaN HEMTs.