Barrier Lowering-Induced Capacitance Increase of Short-Channel Power p-GaN HEMTs at High Temperature

The capacitance–voltage characteristics of short-channel power p-GaN HEMTs from room temperature (RT) to 150 °C are investigated. For the first time, it is found that the OFF-state capacitances at high temperature are substantially higher than the capacitance at RT (i.e., input capacitance
${C}_{ISS}$
, output capacitance
${C}_{OSS}$
, and reverse transfer capacitance
${C}_{RSS}$
increased by 5%, 70%, and 229% at
${V}_{DS} $
= 15 V, respectively). The underlying physical mechanism is explained by the barrier-lowering effect induced by high temperature, which boosts the intrinsic charges and finally leads to the increase of capacitances. This article indicates that the short-channel power p-GaN HEMT capacitances under practical high-temperature operation should be remeasured to evaluate the capacitance-related switching loss more accurately.