Investigation of defects in GaN HFET structures by electroluminescence

This contribution deals with the detection and analysis of electroluminescence emitted by depletion mode (normally-on) InAlN/GaN heterostructure field effect transistors (HFETs) at room temperature and drain-source voltages ranging from 20 to 30 V. Collected electroluminescence maps are used to reveal and localize strong electrically stressed and critical regions of GaN HFETs influencing their functionality and reliability. Such defective regions have been observed along gate fingers as well as at the edges of the drain contact pad expanded outside the transistor structure itself. Identification of observed HFET imperfections provides a valuable feedback towards the optimization of HFET's technology with positive impact on the quality and overall electronic performance of such advanced electronic devices.