Microstructure of Strontium Titanate Thin Film Grown by the Hydrothermal‐Electrochemical Method

Abstract
Microstructures of SrTiO3 thin films grown on Ti substrates by the hydrothermal‐electrochemical method have been studied by transmission electron microscopy. The grown films consisted of a thin surface layer having an isotropic polycrystalline structure and a thick inner layer having a columnar structure. Pores of the order of several tens of nanometers were found at boundaries of columnar grains constituting the inner layer. A 20‐ or 30‐nm‐thick polycrystalline layer of Ti oxides contaminated with a small amount of Sr was also found at the SrTiO3 film/Ti substrate interface. During the film growth at this interface, the observed pores are considered to act as short‐circuit paths for mass transport from the film surface to the interface.