A SPICE-Compatible Equivalent-Circuit Model of Schottky Type p-GaN Gate Power HEMTs with Dynamic Threshold Voltage

In this work, an equivalent-circuit model of Schottky type p-GaN gate power HEMT is proposed and demonstrated using SPICE tools. The SPICE model takes the distinct underlying physics of the p-GaN gate structure into consideration and precisely captures the dynamic threshold voltage (V
TH
) phenomenon. The dynamic V
TH
is an intrinsic property of p-GaN gate HEMT with a Schottky gate contact and is rooted in the fact that the p-GaN layer is floating. The floating p-GaN exhibits a charge storage effect in which it requires higher gate voltage to turn on the transistor from a high-voltage off-state than what is expected from the static device characteristics; thus the dynamic V
TH
is a function of the amount of stored charge. The equivalent model in this work is built according to the charge storage process. The simulated dynamic device characteristics agree well with the experimental results. The influences of the dynamic V
TH
on the waveforms of power switching circuits are predicted and experimentally verified.