Superconductive thin films having transition temperature substantially above the bulk materials

Claim 1

In a method of producing thin films of superconductor materials of the beta-wolfram type having high transition temperatures, the steps comprising (a) assembling within a closed reactor a substrate and a composite containing at least two target materials which when reacted are capable of forming the beta-wolfram crystallographic structure, (b) evacuating the reactor to a pressure not in excess of 5 × 10 -10 Torr while heating the components contained within the reactor to remove all volatile impurities therefrom under said conditions, (c) admitting an inert gas which will support sputtering to the reactor and adjusting the pressure within the reactor with said inert gas to the range between about 2 and 6 × 10 -1 Torr, (d) heating the substrate to a temperature not in excess of about 1000° C, (e) connecting the components within the reactor to a source of DC power while controlling the voltage within the range between about 600 and about 1000 volts and the cathode current density within the range between about 10 and about 50 milliamps per square inch, (f) continuing said sputtering until the desired film thickness is obtained on the substrate, said film having the beta-wolfram structure, and (g) thereafter quenching the deposited film to room temperature.