Degradation mechanisms in AlGaN/GaN high electron mobility transistors have been studied under pinch-off conditions. Sites of localized emission of electroluminescence (EL) in the form of hotspots, known to be related to gate leakage currents, are shown to be the result of the generation of non-radiative recombination centers in the AlGaN device layer during device stress. EL from the hotspot site contains both hot-carrier emission from the acceleration of charge carriers in the device channel and defect-related transitions. Gate leakage through the generated centers is the most likely mechanism for the observation of EL hotspots.
Hodges, C., Killat, N., Kaun, S. W., Wong, M. H., Gao, F., Palacios, T., Mishra, U. K., Speck, J. S., Wolverson, D., & Kuball, M. (2012). Optical investigation of degradation mechanisms in AlGaN/GaN high electron mobility transistors: Generation of non-radiative recombination centers. Applied Physics Letters, 100(11), . https://doi.org/10.1063/1.3693427