Microscopic degradation analysis of RF-stressed AlGaN/GaN HEMTs
An AlGaN/GaN high electron mobility transistor (HEMT) stressed at 10 GHz and increased channel temperatures of T ~ 260 °C has been analyzed by electroluminescence microscopy (ELM) and infrared thermography (IRT). After stress a negative threshold shift is seen in the electrical characteristics. Based on the current dependence of the electroluminescence (EL) intensity image and a local increase of T this shift can be assigned to the degradation of one of its gate fingers. Transmission electron microscopy (TEM) images of this gate finger revealed structural changes along the drain-side edge of the gate.