Abstract
With an in situ low-damage NH 3 -Ar-N 2 plasma pre-gate treatment, a high-quality Al 2 O 3 /GaN-cap interface has been obtained in the Al 2 O 3 /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 ∼10 12 -10 13 cm -2 eV -1 in the Al 2 O 3 /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. © 2013 IEEE.