EPITAXIAL-GROWTH ANALYSIS OF YBACUO THIN-FILMS BY ION BACKSCATTERING AND CHANNELING SPECTROMETRY

He-ion channeling was applied to analyze (1) the preparation of defect-free (100) and (110) SrTiO3, (100) MgO and (100) Zr(Y)O2 surfaces and (2) the growth performance of large-area single-crystalline YBa2Cu3O7-x thin films on these substrates. The polycrystalhne fractions in the film depend on the quality of the substrate surface and on the substrate temperature during deposition. Under optimized growth conditions c-axis-oriented growth is observed with minimum yield values of 2 MeV He ions of 5%, 1% and 10% for films on (100) SrTiO3, (100) MgO and (100) Zr(Y)O2, respectively. From the analysis of angular yield curves it is inferred that the standard deviation of misoriented crystallites is about 0.1°. From the analysis of the Ba-surface peak in comparison with values obtained by Monte Carlo simulation calculations 0.5 to 1 displaced Ba atom per Ba2Y row was obtained indicating that the disordered layer thickness is about 0.3 to 0.6 nm. Ultrathin films with thicknesses down to 2 nm were grown to study the interface disorder. The contribution of interface misfit dislocations to the minimum yield was larger for films on (100) MgO than for films on (100) SrTiO3. It is shown that these latter films with thicknesses of 9 nm and below are partially strained indicating commensurate growth. © 1990.