Large area YBa/sub 2/Cu/sub 3/O/sub 7/ films for high power microwave applications

We have developed large area YBa/sub 2/Cu/sub 3/O/sub 7/ films (/spl ges/2 inch diameter) which have low microwave surface resistance at high microwave power levels. The films are produced by off-axis sputtering using a noncontact direct radiant heating technique. Thickness and composition are uniform to within /spl plusmn/3% and T/sub c/ is uniform to within /spl plusmn/1 K across 3 inch diameter wafers. The microwave surface resistance of these films has been measured over a wide range of temperature (20 K to 80 K) and microwave power. At 20 K, the surface resistance remains below 100 /spl mu//spl Omega/ (at 10 GHz) for microwave surface current densities up to 4.6/spl times/10/sup 6/ A/cm/sup 2/. At 70 K, the surface resistance remains below 350 /spl mu//spl Omega/ (@ 10 GHz) for microwave curent densities up to 1.3/spl times/10/sup 6/ A/cm/sup 2/. High power microwave transmission lines (14 /spl mu/m produced with these films are capable of transmitting microwave power up to +25 dBm (>2.3/spl times/10/sup 6/ A/cm/sup 2/ average current density) at 70 K.<
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