CRYSTAL-GROWTH OF (110) YBA2CU3O7 AND (103) YBA2CU3O7 THIN-FILMS IN-SITU DEPOSITED BY LASER-ABLATION ON (110) SRTIO3 SINGLE-CRYSTAL SUBSTRATES

Epitaxial YBa2Cu3O7-x films have been grown in situ by laser ablation on (110)SrTiO3 substrates and structurally characterized by the following methods: reflection high energy electron diffraction (RHEED), Bragg-Brentano diffractometry, theta-scans, oscillating crystal diffraction, electron channelling patterns (ECPs), scanning tunneling microscopy (STM) and high resolution transmission electron microscopy (HRTEM). We can control two different orientations of the films, corresponding to the (110) and (103) orientations, depending essentially upon the deposition temperature, T(d), with T(d)(110) < T(d)(103), and also upon the oxygen deposition pressure. Deposition on a vicinal surface has resulted, for the first time, in the growth of a (103) film where most of the crystallites have their c-axis aligned. In this case, heteroepitaxy is established, in contrast with the so-called graphoepitaxy previously reported on MgO vicinal surfaces.