On the reverse gate leakage current of AlGaN/GaN high electron mobility transistors

Abstract

In this work, we include the polarization effect within the AlGaN barrier into calculation of the near-surface electrical field ES underneath the Schottky contact metal which determines the field-dependent characteristics of reverse gate leakage current of AlGaN/GaN high electron mobility transistors. High-frequency capacitance-voltage measurement combined with electrostatic analysis is used to estimate ES as a function of reverse bias voltage. The resultant log(I/ES) versus ES curves over a temperature range from 293 to 453 K agree well with the predicted model of Frenkel–Poole (FP) emission of electrons up to the conductive states of threading dislocations. Around zero bias, the reverse polarization-field-induced FP emission current is balanced by a forward defect-assisted tunneling current, both of which follow the same temperature dependent characteristics.