The effect of temperature, growth kinetics, and substrate on the microstructure of RF off-axis sputter deposited YBa{sub 2}Cu{sub 3}O{sub 7} thin films

YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) thin films were grown on single crystal substrates by RF off-axis sputter deposition under different growth condition, systematically varied to change the kinetic and thermodynamic processes that determine both the film microstructure and its crystallographic orientation. The effect of substrate temperature, position, and material, total chamber pressure, and RF power on the final film structure was examined. The growth matrix was bounded by temperatures from 640 to 780C, pressures from 50 to 200 mtorr, and power from 50 to 100 watts. Higher growth rates were achieve by increasing the power setting, lowering the total pressure, and moving the substrate farther into the plasma. Care was taken to stay within these parametric stability limits defining the 123-YBCO growth regime. The resulting films were characterized, primarily, by scanning tunneling and atomic force microscopy, x-ray diffraction, and eddy-current measurements. At the extremes of the growth conditions used in this study, ex-situ examination of the films revealed that they spanned the extremes from all c-axis normal to all a-axis normal material, with mixed a-/c-axis normal material in between extremes in deposition parameter limits, with the mixed films containing a-axis material overlaying a c-axis layer. Smooth single orientation films, suitable for multilayer device structure, could be routinely obtained by controlled growth. Highest surface roughness measurements were usually due to incomplete or non uniform a-axis coverage on c-axis films. Combined data obtained from different studies showed that lower temperatures and higher rates favored a-axis growth under the conditions used in these studies. The YBCO films were more unstable to a cross-over from c-axis to a-a-axis growth when deposited on NdGaO{sub 3} and LaAIO{sub 3} than on SrTiO{sub 3}. Under conditions favoring c-axis perpendicular growth, higher temperatures and rates resulted in rounder islands.