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 YBa₂Cu₃O_7-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.