COEVAPORATED Y-BA-CU-O THIN-FILMS ON DIFFERENT SUBSTRATES

Substrates of SrTiO3 are generally recognized as the most suitable for growing epitaxial superconducting thin films of YBa 2Cu3O7 (YBCO) with high transition temperature and high critical current density. Regardless if different deposition methods such as sputtering, coevaporation, or laser ablation are used, superconducting films with Tc above 90 K and Ic exceeding 106 A/cm2 at 77 K have been prepared on this substrate material. However, SrTiO3 is not suitable for high frequency applications due to its high losses in this regime. It is therefore of interest to study film preparation on other substrates which are better suited for applications. Several alternatives to SrTiO3 have recently been proposed. In this work a comparison is made between coevaporated YBCO layers using the BaF 2 method on seven different, commercially available, single crystal substrate materials.