Initial stage of YBa2Cu3O7−x film growth on SrTiO3

Abstract We observed the epitaxy onset of YBa 2 Cu 3 O 7- x on SrTiO 3 (001) substrates by recording the reflection high-energy electron diffraction pattern in-situ as a function of time. The first “anomalous” patterns were indentified to be due to epitaxial Cu islands which then oxidize to form an average monolayer of epitaxial Cu 2 O before the first YBa 2 Cu 3 O 7- x monolayer nucleates and spreads rapidly incorporating the Cu 2 O. The growth of further layers leads to regular oscillations of the specular beam intensity. The maxima of these oscillations occur prior to layer completion. We argue that this is due to the formation of small islands on the terraces which act as strong scattering centers and thus diminish the specularity before the terraces can coalesce to complete the layer.