Thickness dependence of an amorphous overlayer Ge film on the electrical conductivity of ultrathin Pt films

Abstract

The resistance of ultrathin Pt films as influenced by amorphous Ge thin overlayers has been studied. The ratio of change in resistance of the Pt films with overlays of the amorphous Ge is negligibly small for continuous Pt films but is much larger for semicontinuous and discontinuous Pt films, especially for discontinuous ones: As order, these ratio are 10−2, 1, and 102, respectively. The changes in resistance of semicontinuous and discontinuous Pt films markedly depend on the thickness of the overlay. With the thickness of the overlay, at first, the resistance increases slightly for semicontinuous Pt films and decreases rapidly for the discontinuous one, and then decreases for both films to a saturation value (∠60 Å). The decreases in resistance of both Pt films with the thickness of the overlay can be explained by electrical conduction of the localized states in the energy gap of the overlay.