Characterization of deep levels in lGaN|GaN HEMT by FT-DLTS and current DLTS

In this work, GaN|AlGaN high electron mobility transistor (HEMT) structures are investigated, grown on semi-insulating SiC substrates by molecular beam epitaxy and metal-organic chemical-vapor deposition techniques. This paper reports on the kink effect and hysteresis effect observed in AlGaN|GaN high electron mobility transistors (HEMTs) on SiC substrate. It is well known that trapping effects can limit the output power performance of microwave HEMTs, which is particularly true for the wide band gap devices. A detailed study is presented of FT-DLTS and CDLTS measurements performed on AlGaN|GaN HEMTs. It is demonstrated that the kink effect is directly correlated to shallow traps, and a remarkable correlation exists between deep levels observed by CDLTS and FT-DLTS and the presence of parasitic effects such as kink and hysteresis effects.