YBaCuO thin films on sapphire up to 2-inch-diameter for microwave applications

YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCo) thin films on R-plane sapphire up to 5-cm-diam with ZrO/sub 2/:Y (YSZ) buffer layers were fabricated by in-situ off-axis DC magnetron sputtering-and laser ablation. The film DC properties, critical current density (J/sub c/), effective microwave surface resistance (R/sub s/), X-ray data and surface morphology as functions of deposition temperature (T/sub d/) from 600 to 750/spl deg/C were studied. We have found out that the two processes simultaneously and in different ways affect the YBCO layers superconducting properties versus T/sub d/. The results show that films deposited at both ends of T/sub d/ range have equal critical temperatures but their J/sub c/ and R/sub s/ differ up to an order of magnitude. High-homogeneity 5-cm-diam films with J/sub c/>4 MA/cm/sup 2/ and R/sub s/<0.8, m/spl Omega/ at 10 GHz, and 77 K were routinely fabricated under optimum growth conditions. The effective 2 GHz short-dipole antenna and Wilkinson divider were developed and fabricated from the films.<
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