Electric polarization and diode-like conduction in hydrothermally grown BiFeO3 thin films

We report the successful synthesis of high-quality BiFeO3 thin films on a SrRuO3/SrTiO3 substrate using hydrothermal methods, and their structural, ferroelectric, and electrical properties. Using a low precursor concentration, we obtained compressively strained BiFeO3 thin films (thickness: 60 nm) with smooth surface (roughness: 4.2 nm). The ferroelectric polarization of the BFO thin films was parallel with respect to the normal to the substrate and changed direction by 180 degrees under the application of electric field. The current flowed unidirectionally; such rectifying behavior was attributed to Schottky barrier modulation by oxygen vacancies and ferroelectric polarization. Our results provide an important step in the applications of hydrothermally grown BiFeO3 thin films like a large-area and low-cost photovoltaic device. (C) 2014 Elsevier B.V. All rights reserved.