CRYSTALLINE CHARACTERIZATION BY RUTHERFORD BACKSCATTERING SPECTROMETRY AND ELECTRON CHANNELING OF IN-SITU GROWN YBA2CU3O7 THIN-FILMS DEPOSITED ON (100) MGO BY DC SPUTTERING OR LASER-ABLATION

YBa2Cu3O7 (YBCO) superconducting thin films have been grown in situ on single-crystal (1 00) MgO substrates by single target d.c. sputtering or laser ablation. The films were highly textured, with full c-axis orientation, as shown by standard theta-2theta X-ray diffractometry. The in-plane structure of the films was characterized by reflection high energy electron diffraction (RHEED), oscillating single-crystal photographs, Rutherford backscattering spectrometry (RBS) and by electron channelling patterns (ECP). According to the results obtained from all these methods the films were found to be single-crystal-like. Channelling RBS experiments were carried out in order to provide additional information on the crystal quality, quantitatively evaluated from the chi(min) values:for samples deposited in optimized conditions, we have found these values on sputtered films as well as on laser ablated films deposited on (1 00) MgO substrates to be close to that of the virgin substrate. These values strongly depend on the deposition temperature, in good agreement with ECP data. On the other hand, RBS analysis gives access to the composition of the thin films and in addition the in-depth homogeneity in composition was checked by secondary ion mass spectrometry (SIMS).