Interplay Between Surface and Buffer Traps in Governing Breakdown Characteristics of AlGaN/GaN HEMTs—Part II

Physical insights into the complex interplay of surface and (GaN) buffer traps governing breakdown characteristics of AlGaN/GaN HEMTs are developed by well-calibrated TCAD simulations. Impact of surface traps in correlation with 1) acceptor traps in case of Fe doping and 2) self-compensating traps (corresponding to C doping) in the GaN buffer on breakdown characteristics of AlGaN/GaN HEMTs is discussed. The explorations include defect-related traps as well as traps induced by intentional buffer doping by carbon/iron. The computational findings corroborate well with the experimentally observed electric field profile for devices with different buffer doping conditions. Developed insights have allowed to discuss the collective impact of surface as well as buffer traps on device design to improve breakdown characteristics.