PREPARATION OF VERY LARGE YBCO FILMS ON SINGLE-CRYSTALLINE AND POLYCRYSTALLINE SUBSTRATES

High quality YBa2Cu3O7 thin films on areas of up to 9'' in diameter ha ve been grown by reactive thermal co-evaporation using a rotating subs trate holder. A scanning inductive j(c) probe is used to monitor the h omogeneity of critical current densities which are typically greater t han 2 MA/cm(2) The same technique also allows a double sided depositio n for filter applications. Surface resistance values are found to be b elow 500 mu Omega at 10 GHz. On biaxially aligned buffer layers on pol ycrystalline substrates j, values of 1.4 MA/cm(2) are achieved at 77 I t as well. We have also studied the properties of Nd1-xBa2+xCu3O7 film s grown with the same system.