Measurement of interface-state-density distribution near conduction band at interface between atomic-layer-deposited Al2O3 and silicon-doped InAlN

The Al2O3/InAlN interface formed by atomic layer deposition on a sufficiently thick silicon-doped InAlN layer lattice matched to GaN was investigated electrically. A metal-oxide-semiconductor (MOS) diode fabricated through careful interface formation showed a minimized leakage current and a capacitance-voltage (C-V) characteristic with a capacitance change large enough to evaluate the interface-state density, in the range of 1012 eV−1cm−2, near the conduction band. However, the MOS diode with careless interface formation resulted in degraded electrical characteristics, which indicated the process dependence of the interface properties. The effects of the acceptor-like interface states on the C-V curves are discussed.