Highly thermally stable in situ SiN_X passivation AlGaN/GaN enhancement-mode high electron mobility transistors using TiW refractory gate structure

This study examines the properties of in situ SiN_x surface-passivated enhancement-mode (E-mode) AlGaN/GaN high electron mobility transistors that are made with refractory titanium tungsten (TiW) and traditional nickel gate metals. Traditional Ni/AlGaN Schottky interfaces form intermixing states under a thermal stress of 400 °C. The maximum transconductance (g_m) of TiW-gate devices is reduced by 10% as the temperature of the device increases from 300 to 400 K, whereas that of traditional Ni-gate devices is reduced by 24%. The Ni/AlGaN intermixing states increase the trap activation energy (123 meV) of the Ni-gate device. The refractory TiW metal thus has great potential for use in E-mode GaN power electronics.