Properties of metal/n-GaN Schottky and PCVD-SiO(2)n-GaN interfaces, includi
ng the effect of thermal annealing, have been investigated by I-V-T, C-V an
d C-t measurements. I-V-T characteristics of the Schottky diodes indicate t
hat reported large discrepancies in the Schottky barrier height (SBH) betwe
en I-V and C-V measurements, scattered Richardson constants, and I-V should
ers are well explained by superposed cut-rent arising from "surface patches
" with low SBHs. A low-temperature annealing in N-2 is highly effective to
improve the uniformity of the SBH. For the as-deposited SiO2/n-GaN sample,
the interface Fermi level locates at about 0.2 eV from the conduction band
edge under thermal equilibrium condition, and the value increased to 0.5 eV
after annealing in H-2 at 500 degrees C. A relatively small band bending w
as also confirmed from C-t measurement. The minimum interface state density
of 2 x 10(11) cm(-2) eV(-1) for the as-deposited interface reduced to one-
third after the annealing. (C) 2000 Elsevier Science B.V. All rights reserv
ed.