Application of high rate magnetron sputtering to the fabrication of A-15 compounds

High quality Nb3Sn films have been fabricated using a recently developed magnetron sputtering process capable of deposition rates approaching 1 μm/min. at sputtering voltages less than 500 V and power levels of about 5 KW. Low sputtering voltages allow more complete thermalization at lower pressures of the material condensing on the substrate which can improve long range order. Transition temperatures of up to 18.3 ° K, Jc(O)'s of 15 × 106A/cm2and Hc2as high as 240 kOe have been achieved in 1-3 μm films deposited from a Nb3Sn reacted powder target with substrate temperatures between 600 and 800°C. The films exhibit smooth surfaces and, generally, apreferred orientation. The growth of the film is columnar in nature. The sputtering parameters, substrate material and temperature will be related to film structure, Tcand Jc(H,T) and the Nb/Sn ratio as determined by Rutherford backscattering.