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 IG, with only a slight degradation of drain current ID. 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 IG and electroluminescence intensity and with an enhancement of trapping effects such as current collapse.