Study of Drain-current Collapse in AlGaN/GaN MIS-HEMTs with Different Gate Lengths

Currently, the current collapse phenomenon in normally-on GaN MIS-HEMTs with different gate lengths has not been thoroughly investigated. In this work, three DUTs of the same size with different gate lengths of 3/6/8 μm were chosen to study current collapse during off-/on-state stress. It is found that current collapse is suppressed under on-state stress due to the formation of de-trapping paths. Current collapse is severe at high-drain off-state stress due to activated traps in the AlGaN barrier layer. Moreover, the current collapse is more severe with decreasing gate lengths, which means more interface traps are exposed to the access region.