Charge-Based Compact Model of Gate Leakage Current for AlInN/GaN and AlGaN/GaN HEMTs

The gate leakage current is analytically modeled for AlInN/GaN and AlGaN/GaN high-electron mobility transistor (HEMT) devices using a charge-based approach. Four different current mechanisms, namely Fowler-Nordheim tunneling (FNT), Poole-Frenkel emission (PFE), thermionic emission (TE), and defect-assisted tunneling (DAT) are considered. FNT and PFE are two dominant mechanisms in the reverse bias region, while TE and DAT are significant in forward and near zero gate bias regions, respectively. This model is implemented in Verilog-A and validated by comparison with experimental data for both AlInN/GaN and AlGaN/GaN HEMTs. It is shown that the model is able to capture the effects of Al molar fraction, barrier thickness, and temperature on gate leakage current over a wide range of gate and drain voltages.