Electrical characterization of n-GaN Schottky and PCVD-SiO2/n-GaN interfaces

The electrical properties of metal/n-GaN and PCVD-SiO2/n-GaN interfaces are investigated by measuring I-V and C-V characteristics of Schottky and MTS diodes, it is found that the Schottky barrier height is predominantly determined by the metal work function, although additional currents superposed on thermionic emission current sometimes modify the true Schottky barrier height. For PCVD-SiO2/n-GaN interface, C-V measurements indicate that the Fermi level locates at 0.32 eV from the conduction band edge under thermal equilibrium condition and it can move within the upper forbidden band gap with the applied gate bias. The minimum interface state density as found to be 1-2 x 10(11) cm(-2) eV(-1). (C) 1998 Elsevier Science B.V. All rights reserved.