How epitaxial are Pd₂SiSi interfaces?

Pd₂Si layers produced by evaporation or sputtering onto silicon substrates were examined by high resolution electron microscopy, microdiffraction, X-ray, energy loss and Auger spectroscopy. The SiPd₂Si interfaces produced by evaporation were in all cases rougher and more polycrystalline than those produced by sputtering. X-ray microanalysis showed the predictable variation in palladium distribution across the interface but quantification did not produce the expected palladium-to-silicon ratios, primarily because of probe broadening and X-ray-induced fluorescence. Energy loss spectra showed plasmon energy shifts and changes in Si L edge shape due to bond formation with palladium. Auger data provided evidence for a small amount of oxygen at the SiPd₂ interface. Electrical measurements of the ideality factor for Schottky barriers made from these materials produced higher values for the rougher evaporation-formed interfaces consistent with interface-roughness-induced scattering and carrier recombination.