Low temperature growth of epitaxial ferroelectric BaTiO₃

BaTiO3 exhibits several functional properties, such as high dielectric constant, large Pockels coefficient, and strong ferroelectricity/piezoelectricity. These properties can be used for a variety of applications, such as ferroelectric tunnel junctions in non-volatile memory devices. To achieve large-scale integration of BaTiO3, however, one requires the synthesis of high-quality BaTiO3 films at low temperatures in order to be compatible with the thermal budget of electronic processes in use today. Here, we describe the synthesis of BaTiO3 thin films by molecular beam epitaxy and find that coherently strained and ferroelectric BaTiO3 can be grown at temperatures as low as 310 °C. Using reflection high energy diffraction, we demonstrate a surface mobility of BaO and TiO2 adatoms that is high enough to promote ferroelectric crystal growth at low temperatures. A clear ferroelectric polarization switching is observed using piezoresponse force microscopy. Our results pave the way toward large-scale integration of ferroelectric BaTiO3 with mainstream electronics platforms.