The nucleation of high-<i>T</i> <i>c</i> Nb3Ge in the presence of impurities

Abstract

Analyses of high-Tc Nb3Ge films show that they all have a peak in oxygen concentration near the substrate-film interface and that their lattice parameters in that region are abnormally large. It is proposed that high-Tc Nb3Ge is a metastable phase which is formed via a homoepitaxial process from a large lattice parameter A15 Nb-Ge phase. This phase near the interface is believed stable due to an expanded lattice resulting from the presence of impurities.