Gate current degradation in W-band InAlN/AlN/GaN HEMTs under gate stress

Schottky gate degradation of W-band InAlN/AlN/GaN high-electron-mobility transistors (HEMTs) has been studied under prolonged positive gate stress. Two different degradation mechanisms have been identified. In an early stage, a gate leakage current increase takes place without any observable drain current nor source and drain resistance degradation. We propose electric field induced trap generation in the AlN barrier layer as the cause. Under harsher gate stress, a second degradation mechanism kicks in where gate leakage current, as well as drain current and the source and drain resistances degrade significantly. We attribute this to Schottky barrier degradation due to severe local self-heating.
National Reconnaissance Office (Contract DII NRO000-13C0309)