Superconducting properties of getter-sputtered V3Al thin films as a function of sputtering gas, pressure, and substrate temperature

Abstract

Superconducting transition temperatures of V₃Al thin films prepared by getter sputtering have been found to vary significantly not only with variation of the deposition temperature, as previously reported, but also with variation of the deposition pressure and composition of the sputtering atmosphere. The film composition measured at T_c maxima obtained by varying the deposition temperature for nonoptimum pressures was found to depart significantly from the 3 : 1 stoichiometry. High‐deposition pressures P_D ≳175 mTorr are associated with films containing an excess of Al, while deposition pressures of less than 60 mTorr result in V‐rich films. With near‐optimum film deposition conditions for Ar, 155 mTorr pressure, and a deposition temperature of 800 °C, we have obtained a peak superconducting transition temperature of 11.8 °K.