Low-temperature growth of epitaxial barium titanate thin films by irradiation of low-energy positive oxygen ions

Barium titanate (BaTiO3) thin films were deposited by a molecular beam epitaxy (MBE) system. The epitaxial temperature of BaTiO3 thin films on strontium titanate (SrTiO3) single crystals decreased from 600 degrees C to 400 degrees C by irradiation of positive oxygen ions with low energy generated from an electron cyclotron resonance source (ECR-gun). The energy of ionized oxygen fluxes was controlled by two voltages: the accelerating voltage (V-a) and the bias voltage (V-b). At 400 degrees C, the BaTiO3 thin films were epitaxially grown at V-a=+50 V and V-b=100 V. The irradiation of low-energy positive oxygen ions was effective for both oxidation in a high vacuum and reducing crystallization temperature.