Study of 2D growth stability of SrRuO3 on SrTiO3

Abstract

In order to control the surface roughness and chemical termination of an oxide film, a promising route is to use a vicinal substrate and to control the atomic step positions during growth in the so-called step flow mode. The stability of this mode is studied in the case of SrRuO3 heteroepitaxy on SrTiO3, focusing on the influence of deposition flux and substrate mean terrace width. Transitions from unstable step bunching to stable step flow and from step flow to island nucleation are observed and discussed in terms of the mean step velocity. The step bunching is traced back to a strain-based driving force in competition with a stabilizing asymmetry for incorporation of adatoms at steps. A thin film obtained after stable step flow gives a greater finite size effect than a step-bunched one, as seen by X-ray diffraction.