Impact of p-GaN layer doping on switching performance of enhancement mode GaN devices

Enhancement type p-GaN HEMT devices are desirable in power converter circuits for a failsafe operation. The gate capacitance of these devices decreases for higher gate bias due to junction capacitance of the Schottky metallp-GaN junction. It is important to capture this effect in simulation model. To this end, for the first time, we present a depletion approximation based analytical model which effectively models this effect in the device. Using device electrostatics at the p-GaN/AlGaN junction in conjunction with physics-based Advanced Spice Model for High Electron Mobility Transistor (ASM-HEMT) as the core, we model the effect of doping in p-GaN layer in the GaN devices. We studied this device phenomenon and its effects on the performance of the switching characteristics of enhancement mode GaN power devices.