Localized Damage in AlGaN/GaN HEMTs Induced by Reverse-Bias Testing

Reverse-bias testing in AlGaN/GaN HEMTs at high (negative) gate voltage is found to induce a catastrophic increase in gate leakage current I-G, with only a slight degradation of drain current I-D. Electroluminescence (EL) microscopy demonstrates that leakage current injection is localized within "hot spots" at the gate edges, possibly corresponding to defects in the semiconductor material or at the metal-semiconductor interface. The density of "hot spots" increases during tests and is correlated with the increase of I-G and electroluminescence intensity and with an enhancement of trapping effects such as current collapse.