DOUBLE-SIDED YBCO FILMS ON 4-INCH SUBSTRATES BY THERMAL REACTIVE EVAPORATION

Homogenous high quality YBa2Cu3O7 films on large substrates are first essentials of the commercialization of HTSC devices. We have employed thermal co-evaporation to deposit YBa2Cu3O7 films up to 4'' diameter. The heater design allows intermittent metal deposition and oxidation in spatially separated zones, with the metal deposition in vacuum and the oxidation at 10(-2) mbar. On all substrates from MgO, LaAlO3, YSZ, sapphire to Si and GaAs we typically achieved T-c > 86 K and j(c) > 2.10(6) A/cm(2) over the entire area. The radiation heating allows us to turn the substrates over for double sided coating. On 2'' and 3'' LaAlO3 and on 4'' YSZ, both sides meet the above specifications even for thicknesses up to 400 nm.