The location of conductance stability related deep-level defects in GaN based power HEMTs on Si substrate

Abstract The charging effect of deep-level defects (DLD) in GaN based power high electron mobility transistors (HEMTs) on Si substrate is one of the reasons for their conductance stability issues during the switching loop, yet a comprehensive understanding of their behaviors on channel conductance is still lacking. In this study, in addition to the acceptor DLD resulted from the carbon doping, a donor-like DLD was observed with its energy level, and its physical location in the AlGaN/GaN HEMT epi-structure was also confirmed by using channel transient current measurement under the negative substrate bias condition. By the assistance of finite element numerical simulation, the transient current behavior was believed to be decided by the ionizing competition process between the deep donor and deep acceptor under the substrate bias induced electric field, which is due to the differences in density, ionization energy, and the ionizing time constant of both donor- and acceptor-DLD.