Discrete Schottky barriers observed for the metal/n-ZnSe(100) system

We report on the formation of discrete Schottky barriers for Au, Ag and Sb contacts to chemically etched n-ZnSe/n(+)GaAs(100). For Au/n-ZnSe phi(b) = 0.9, 1.2, 1.45 and 1.65 +/- 0.04 eV, for Ag/n-ZnSe phi(b) = 1.2 and 1.45 +/- 0.04 eV and for Sb/n-ZnSe phi(b) = 1.45, 1.65, 1.8 and 2.1 +/- 0.04 eV were repeatedly observed. Often the barrier height was seen to vary from contact to contact on the same sample. The barrier heights appear to be independent of the metal used but correlated well with reported deep levels. These findings combined with the ageing properties of Au/n-ZnSe(100) devices in particular leads us to the conclusion that Fermi level pinning by native defects is a dominant mechanism in Schottky barrier formation in these systems.