Low-temperature synthesis of BaTiO₃ thin film by molecular beam epitaxy

The perovskite oxide BaTiO₃ is a lead-free material with high performance ferroelectric/piezoelectric properties. Integrating BaTiO₃ with existing semiconductor technology requires the synthesis of high-quality BaTiO₃ in the thin-film form at low temperatures to decrease the thermal budget during device fabrication. We describe our synthesis of BaTiO₃ thin films by molecular beam epitaxy at various temperatures and find that coherently strained BaTiO₃ can be grown at a temperature as low as 280 °C. The growth mechanism and strain state of these films are characterized as a function of temperature using x-ray diffraction and in-situ reflection high-energy electron diffraction. Our results pave the way toward large-scale integration of BaTiO₃ with semiconductor technology.