Performance optimization of lateral AlGaN/GaN HEMTs with cap gate on 150-mm silicon substrate

•An innovative gate structure of AlGaN/GaN HEMT called “Cap Gate” is proposed.•Lower leakage current has been obtained by optimizing gate layout with “Cap Gate”.•The scaling down LG (with LG+2LCG constantly) contributes to the on resistance.•The BV and current capacity of “cap gate” HEMT are also be studied.