Atomic-scale visualization of initial growth of perovskites on SrTiO3(001) using scanning tunneling microscope

Abstract

The growth of perovskite oxide films is known to be strongly influenced by both substrate surface lattice symmetry and stoichiometry. However, this has been postulated mainly based on indirect evidences. Scanning tunneling microscopy (STM) is unambiguously capable of identifying the real-space distribution of the structural and electronic properties of solid surfaces. Therefore, oxide film growth technologies combined with STM are strongly desirable for resolving atomic-scale growth mechanisms of perovskite thin films. Here, we review recent advances in STM studies on initial growth stages of perovskite oxides on SrTiO3(001). First, we introduce surface terminations and reconstructions of SrTiO3(001), as well as their influence on the initial growth of perovskite films studied by STM on an atomic-scale, followed by a discussion of a feasible model for the surface atomic structures and chemistries behind such growth behaviors. We then introduce studies on the growth dynamics of perovskite oxides on SrTiO3(001) in terms of temperature (T) and thickness-resolved STM: (1) Layer-by-layer identification of T-dependent surface structures of ultrathin SrRuO3, suggesting a dramatic change in the surface migration barrier caused by switching of the surface terminations and (2) a prototypical study on the surface diffusion dynamics in perovskite growth realized by the application of the classical diffusion model to the island nucleation stage of SrTiO3 homoepitaxy.