Reliability and failure analysis of 100 nm AlGaN/GaN HEMTs under DC and RF Stress

Degradation of 100 nm AlGaN/GaN HEMTs under DC and 10 GHz stress conditions has been compared and a promising median lifetime of more than 2000 h under RF stress in air at a drain voltage of 15 V and an average channel temperature of 230°C has been achieved. It has been found that the devices degrade faster under RF stress compared to DC stress. Physical failure analysis using electroluminescence imaging, TEM and EDX cross-sections parallel and perpendicular to the gate finger shows that the local oxidation induced pit formation beside the gate foot and the interdiffusion of Pt with Al, Ga and N are the main failure mechanisms causing the degradation in saturation current and increase of leakage current of DC stressed devices.