Performance improvement in NiO x -based GaN MOS-HEMTs

Abstract

Abstract We have illustrated the thermal oxidation of Ni as gate dielectrics to improve the characteristics of GaN-based metal oxide semiconductor high electron mobility transistors (HEMTs). The oxide is formed by a pre-deposition of a thin film followed by oxidation in pure O2 ambient. The formation and thickness of the oxides are confirmed through x-ray photoelectron spectroscopy and transmission electron microscopy. NiO x is found to have an energy band gap of 3.7 eV determined using O 1s energy loss spectra. NiO x is found to provide negative (1.7 eV) valence band offsets with AlGaN. The potential use of the oxides has been confirmed by the significant improvement in drive current, transconductance, subthreshold swing, unity current gain frequency, and gate current leakage over the Schottky barrier HEMTs (SB-HEMTs). We have observed a positive shift in threshold voltage for NiO x -based gate dielectric devices compared to that of the SB-HEMTs.