TEMPERATURE-DEPENDENCE OF THE SCHOTTKY-BARRIER IN AL ALGAAS METAL-SEMICONDUCTOR JUNCTIONS/

The dependence on temperature and alloy composition of the Schottky ba rrier height of Al on AlxGa1-xAs metal-semiconductor junctions for n- and p-type substrates and 0 < x < 1 is reported. All the structures we re grown by molecular beam epitaxy. The compositional dependence of th e barrier heights is the same as that of the band offsets in GaAs/GaAl As heterojunctions. The barrier height for the p-type substrates is pr actically independent of temperature over the whole composition range, while for the n-type substrates the temperature change of the Schottk y barrier follows that of the energy gap. This observation questions v alidity of the class of models of the Schottky barrier formation based on the concept of a neutrality level. Such behavior can, however, be reconciled if localized defects, whose ground-state wave function is o f a bonding type are the source of the Fermi-level pinning at the inte rface.