Reflection high-energy electron diffraction and atomic force microscopy studies on homoepitaxial growth of SrTiO 3(001)

Abstract

This paper reports a systematic study on the homoepitaxial growth of SrTiO 3(001) conducted using reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM) in order to improve our understanding of the basic processes in the epitaxial growth of perovskite thin films. Under certain growth conditions, the homoepitaxial growth of SrTiO 3 essentially proceeds in the layer-by-layer (2D nucleation) growth mode with the basic unit of a molecular layer. This cyclic process due to unit-cell-by-unit-cell (uc-by-uc) growth is confirmed by undamped RHEED oscillations and the corresponding temporal evolution of AFM images of the growth front. Furthermore, the surface mobility is controlled by growth temperature and oxidation condition. By changing growth temperature or oxidation condition, crossovers from layer-by-layer growth to step-flow like growth and from layer-by-layer growth to 3D island growth through Stranski–Krastanov growth are observed. On the basis of these results, a universal phase diagram is proposed for the growth mode of the epitaxial film growth of complex oxides.