Synthesis of Nb3Al Thin Films by Magnetron Sputtering

Abstract
Nb3Al thin films with the highest T c (16.7 K) among as-sputtered films ever reported have been prepared by magnetron sputtering from an arc-melted target. Metallurgical phases, lattice constants, and superconducting T c's of films were determined as a function of substrate temperature and Ar pressure. Maximum T c's were found in the films deposited at 650–700°C, which have an A15 structure with a slight amount of Nb2Al phase. For films deposited at Ar pressures lower than 10Pa, a systematic decrease in T c was found. This result suggests the importance of thermalization and low substrate bombardment in obtaining high-T c as-sputtered Nb3Al thin films.