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

Microstructures of SrTiO 3 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 SrTiO 3 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.