Preparation and properties of high-Tc Nb–Ge films

Using a previously reported low-energy sputtering technique, Nb-Ge films have been prepared with superconducting Tc's up to ∼23 K. High-field, x-ray, and annealing results are reported for these highest-Tc films. A discussion of the critical parameters required to achieve the highest transition temperatures in the Nb–Ge system is given. Also further arguments in support of the theories that these highest Tc's are due to the formation of the stoichiometric Nb3Ge phase in the sputtered films are presented.