Schottky barrier height on thermally oxidized InAlN surface evaluated by electrical and optical measurements

Current transport and Schottky barrier height analysis on InAlN/GaN structures with thermally oxidized InAlN surface (800 °C, 1 min) was performed. From the current-voltage characteristics measured at various temperatures (300–820 K) and their approximation by various current mechanisms, it follows that the tunneling current dominates. Extraction of the thermionic emission yielded the Schottky barrier height of 2.43 eV at 300 K and its slight decrease with increased temperature. Optical method (photoemission current vs photon energy) allows direct barrier height evaluation without analyzing current mechanisms. Comparative analysis using optical method yielded the room-temperature barrier height of 2.57 eV. Obtained barrier heights document significant barrier enhancement due an InAlN oxidation. This result confirms the thermal oxidation procedure as a useful tool at the preparation of reliable InAlN-based devices.