Surface Step Density Oscillation During the Growth of Yba₂Cu₃O₇__X and Dyba₂Cu₃O₇„_X Superconducting Thin Films

Intensity oscillations of the specular reflection high-energy electron diffraction (RHEED) beam observed during the growth of YBa₂Cu₃O₇__x and DyBa₂Cu₃O₇__x thin films on (100) SrTiO₃ substrates have been analyzed within the framework of an analytical model. Monte Carlo studies have also been carried out. Results of both of these studies are in agreement with experimental data and support the proposition that the RHEED intensity oscillations in these systems are a consequence of changing surface step density, caused by cycles of nucleation and coalescence. Differing time periods for RHEED oscillations of the Dy and Y compounds are shown to be the consequence of differing vapor pressures at the substrate temperature.