Breakdown voltage enhancement in field plated AIGaN/GaN-on-Si HFETs using mesa-first prepassivation process

It has been found that the field plate metal in direct contact with the mesa sidewall in a conventional prepassivation process is responsible for the early breakdown phenomenon in field plated AlGaN/GaN-on-Si heterojunction field-effect transistors (HFETs). The breakdown voltage characteristics of the field plated AlGaN/GaN-on-Si HFETs fabricated using two different prepassivation processes were investigated as a function of field plate length. The breakdown voltages were significantly enhanced by employing the mesa-first prepassivation process in which the field plate was separated from the mesa edge by the passivation layer.