Sputtering of high t/sub c/ Nb3Ge and Nb3Si

Observations are reported of two effects that relate to the formation of high T/sub c/ Nb3Ge and Nb3Si A15 phases using a DC getter sputtering technique. The first is an effect associated with convection of the sputtering gas which has been studied by tilting of sample substrates and heater with respect to the horizontal. The second effect is associated with surface markings on the films, in particular in the Nb-Si system. These observations constitute further evidence of the complexity of this sputtering process and indicate that, unless there is careful control of the experimental conditions, the deposition parameters and the film properties are likely to vary locally on a rather small scale. Some of the reservations concerning the high T/sub c/ values observed in the Nb-Si system are discussed