Importance of the Gate-Dependent Polarization Charge on the Operation of GaN HEMTs

We investigate the influence of the gate-voltage dependence of the polarization charge on the electron sheet charge density in the channel and how it reflects on the device transfer and output characteristics in GaN HEMTs. We find that a 10% increase in the polarization charge is needed to match the experimental data when the gate-voltage dependence of the polarization charge is included in the theoretical model. This information is important for calibration in commercial device simulators and for better understanding of the quality of the GaN/AlGaN interface.