Electroluminescence analysis of HFET's breakdown

In this letter, we correlate different breakdown mechanisms occurring near pinch-off and in off-state conditions in power AlGaAs/GaAs heterojunction FETs (HFETs), operated in "three terminals" (on-state) and "two-terminals" (off-state) modes, to electroluminescence emission due to high energy carriers, electrons, and holes. In particular we will use spectral analysis and spatially resolved emission analysis in order to identify regions of the device where hot and cold carriers emit light. We will show how under "three-terminals" breakdown conditions high energy carriers emit light at the drain side of the gate while cold carriers recombine mostly at the source side of the gate.