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Interface Band Structure Effects
Marked differences in the attenuation length of hot electrons are observed at biases near the Schottky barrier depending upon the substrate orientation, increasing by an order of magnitude for Si(001) and not for Si(111). These results provide clear evidence that the crystallographic orientation of the semiconductor substrate and parallel momentum conservation affect the charge transport across these interfaces. A theoretical model reproduces the effect that combines a free-electron description within the metal with an ab-initio description of the electronic structure of the semiconductor. The attenuation length for the (001) semiconductor orientation can be ascribed to the presence of a focused and dispersion-less ballistic channel at the bottom of the Si(001) conduction band edge that is not present on Si(111).