A study was made of the orientation control of YBa2Cu3O7-x thin films having high crystallinity, high critical temperature and narrow transition width. Thin films with c-axis orientation, a-axis orientation or (110) orientation were prepared by deposition onto SrTiO3 (100) and (110) substrates, using a direct-current magnetron sputtering system. No post-annealing process was introduced. It was found that, with decreasing deposition rate, the critical temperature increased and the transition width narrowed. This suggested a linear relationship between deposition rate and O diffusion coefficient. It was concluded that molecular O was effectively taken into the film during sputtering; implying an activation energy of 0.96eV for O diffusion.

Control of Crystal Orientation in YBCO Thin Films by an Oxygen Diffusion Process. T.Uchiyama, I.Iguchi: Superconductor Science and Technology, 2004, 17[4], 592-5