ABSTRACT
Electrical properties of metal/n-GaN and PCVD-SiO2/n-GaN interfaces have been investigated by I-V and C-V measurements of Schottky and MIS diodes. Although the Schottky barrier height, ϕ bn, was predominantly determined by the metal work function, χ m, with a large S( = d ϕ bn/d χ m) value, a native oxide of GaN surface modified the ϕ bn. When Au, Ni/n-GaN samples were annealed in N2 (below 500°C), the ϕ bn changed with annealing temperature, without any degradation of the Schottky characteristics. For PCVD-Si02/n-GaN interface, it is found that the Fermi level can move within the upper two fifths of the semiconductor band gap. A brief annealing in H2 (between 300-500°C) was highly effective to improve the interface properties, and the minimum state density less than 1 × 1011 cm-2eV-1 was achieved.
