Suppressed current collapse and improved threshold voltage stability of AlGaN/GaN HEMT via O2 plasma treatment

Abstract

A comprehensive study about the effects of O2 plasma treatment on the dynamic performance of AlGaN/GaN high electron mobility transistors (HEMTs) is presented. The drain current transient spectroscopy indicated a much decelerated and mitigated current degradation process for the HEMT with O2 plasma treatment. Upon negative gate bias stressing, current collapse of 10.7 % and minor threshold voltage shift of 0.16 V were achieved by O2 plasma treatment. In addition, current collapse ratio of the HEMTs as a function of stress/recovery time showed that the HEMT with O2 plasma treatment had a superior performance in various on-off conditions. Particularly in high-frequency switching events, current collapse ratio was reduced from about 50 % to 0.2 %. At last, the quality of AlGaN/metal interface with O2 plasma treatment is demonstrated by capacitance-frequency measurements, with the interface trap density Dit is estimated to be 1.39 × 1012 cm−2 eV−1. These results indicate that GaN HEMT with O2 plasma treatment is a promising technology in power switching applications.