SPUTTER-DEPOSITION OF LARGE-AREA YBA2CU3O7-DELTA THIN-FILMS

The utilization of a sputtering system equipped with three planar magnetron guns in off-axis geometry results in very homogeneous films spreading an area of two inches in diameter. During deposition the substrate is directly heated by the thermal radiation of quartz lamps. No thermal contact is required between the heater and the substrate. The temperature of the substrate surface is controlled using an infrared pyrometer with adapted emissivity calibration taking into account the different optical properties of the film and the substrate. In DC resistance measurements the films show a T-c around 90 K and a superlinear temperature dependence in the normal state. The resistance ratio Gamma = R(300K)/R(100K) ranges up to 4.0 and the resistance at T=0 clearly extrapolates to negative values.