Temperature dependence of RHEED oscillation in homoepitaxial growth of SrTiO 3(100) films on stepped substrates

Abstract

Homoepitaxial growth of SrTiO 3 (STO) films on STO(100) substrates with unit-cell-high steps manifests itself by a marked change in the intensity oscillations of the specular reflectivity of reflection high-energy electron diffraction (RHEED) oscillations with increasing temperature. Atomic force microscopy (AFM) revealed a high density of growing islands distributed all over the edges and terraces of the pre-existing steps at lower deposition temperatures. In response, the RHEED intensity exhibits an ‘overdamped’ profile with no oscillation. At higher deposition temperatures ( T s≈500°C), larger (≈40 nm) but fewer islands were observed to form preferentially on the step edges with a gradually recovered RHEED intensity, followed by RHEED oscillations after a few monolayers of coverage. At even higher growth temperatures, immediate periodic oscillations in RHEED intensity were observed. However, the temperature dependence of the oscillation period indicates that it may not be directly related to a layer-by-layer growth mode, as is generally believed.