A new model for the gate leakage current in AlGaN/GaN HFETs is demonstrated. The model is completely physical and is based on the formulation of space charge limited current flow. Two levels of shallow traps in the AlGaN surface layer are considered to evaluate the model. The depth of the traps is consistent with the reports presented in the literature. The model adequately explains the measured gate leakage current and for the first time, predicts accurately the experimentally observed change in slope of the gate leakage current versus the gate to drain voltage. (C) 2012 Elsevier Ltd. All rights reserved.