Mapping of Interface Traps in High-Performance Al2O3/AlGaN/GaN MIS-Heterostructures Using Frequency- and Temperature-Dependent C-V Techniques

With an in situ low-damage NH3-Ar-N-2 plasma pre-gate treatment, a high-quality Al2O3/GaN-cap interface has been obtained in the Al2O3/GaN/AlGaN/GaN MIS-structures. Frequency- and temperature-dependent C-V characterization techniques were developed to map the interface trap density (D-it) at the dielectric/III-nitride interface, whereby a low D-it of similar to 10(12)-10(13) cm(-2)eV(-1) in the Al2O3/GaN/AlGaN/GaN MIS-structures was extracted. The mechanism for the high-quality interface was validated to be effective removal of native oxide and the subsequent formation of a monocrystal-like nitridation inter-layer on the GaN surface. Both D-it mapping and the pre-gate treatment techniques are of significance for the improvement of III-nitride MIS-HEMTs.