Normally-OFF p-GaN Gate Double-Channel HEMT With Suppressed Hot-Electron-Induced Dynamic ON-Resistance Degradation

Hot electrons with high kinetic energy could be generated in the channel of GaN high-electron-mobility transistors (HEMTs) during hard switching operation. Those “lucky” hot electrons scattered to the vulnerable interface between the passivation and barrier layers could bombard the interface region and create new defects that would lead to degradation of the dynamic on-resistance ( ${R}_{ON}$ ) after long-term operations. In this work, we propose a solution to the hot-electron induced device degradation through channel engineering, i.e., deploying a double-channel structure in place of the conventional single-channel structure in ${p}$ -GaN gate HEMTs. It is revealed that hot electrons are mostly generated in the lower channel and thus the additional scattering interface can effectively deter the hot electrons from reaching the vulnerable surface. Dynamic ${R}_{ON}$ degradation induced by long-term stresses at “semi-on” states is shown to be substantially suppressed in the ${p}$ -GaN gate HEMT with the double-channel structure.