Effect of SiO2Surface Passivation on the Performance of GaN Polarization Superjunction Heterojunction Field Effect Transistors

Abstract

In this article, the effects of the SiO2surface passivation layer are reported on normally‐on 1.2 kV GaN polarization superjunction (PSJ) heterojunction field effect transistors (HFETs) by comparing the electrical performances of PSJ HFETs with and without SiO2surface passivation. A slight recovery of the 2D electron gas sheet density is observed in the slight negative shift ofVthafter SiO2surface passivation. Passivation also increases the breakdown voltage. This improvement may result from removing positive surface charges in defects along the P‐GaN gate sidewall and top u‐GaN layer after the specifically designed SiO2surface passivation. Furthermore, the SiO2surface passivation can also effectively suppress the surface gate leakage currents in the PSJ HFETs by eliminating the conductive channel created by the positive surface charges in defects.