Method of preparing thin film of superconductor

Abstract

A method for preparing a thin film of superconductor on a substrate by sputtering. A target prepared from an oxide containing Ba, Y, and Cu in atomic ratios Cu/Y of 2.5 to 3.5 and Ba/Y of 1.8 to 2.2 is employed to form by sputtering a superconducting thin film on a substrate at a temperature of 600.degree. to 800.degree. C. in an atmosphere having total gas pressure of 1.times.10.sup.-2 to 5.times.10.sup.-2 Torr. and containing Ar and O.sub.2 with an O.sub.2 content of 5 to 80 vol. %. The thin film thus formed is subjected to heat treatment at a temperature of 600.degree. to 930.degree. C. for 1 to 30 hours. The thin film after the heat treatment is cooled at a rate not more than 4.degree. C./min. The film forming surface of the substrate is chosen from the (100) surface or the (110) surface of a single crystal substrate which is lattice-matched with the (100) surface or the (110) surface of crystalline Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-n, where n represents a number in the range 0.ltoreq.n<1.

Dependencies are inferred from the claim text.