Tunneling spectroscopy in thin films of vanadium

Vanadium-lead tunnel junctions with vanadium oxide, carbon, and silicon barriers have been studied. Junction characteristics for V--Si--Pb are nearly ideal and yield a ratio 2..delta../sub V/(0)/kT/sub c/ which agrees with BCS theory. The ratio is less for the other junctions. Features due to peaks in the phonon spectrum of vanadium were not observed in the V--Si--Pb junction characteristics, which may be explained by the hypothesis of a thin normal layer on the vanadium surface.