Signatures of the semiconductor crystallographic orientation on the charge transport across non-epitaxial diodes

The hot electron attenuation length of Ag is measured utilizing ballistic electron emission microscopy on nanoscale Schottky diodes for Si(001) and Si(111) substrates. Marked differences in the attenuation length are observed at biases near the Schottky barrier depending upon the substrate orientation, increasing by an order of magnitude only for Si(001). 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.