Structural and electrophysical properties of barium titanate epitaxial films

One of the rapidly developing areas of nanophotonics is the creation of integrated optical circuits for the operation of ultrafast, energy-efficient devices. Electro-optical modulators are the integral part of such systems. The possibility of optical modulation is provided by the electro-optical effect occurring in the waveguide structure and providing the opportunity to manage the optical properties of waveguide materials under the influence of electric fields. Barium titanate BaTiO3 (BTO) exhibits one of the largest known electro-optical coefficients, which makes it an ideal candidate for use in photonic integrated circuit modulators. This work is dedicated to the fabrication of BTO/MgO(001) epitaxial heterostructures and to characterization of their structural and electrophysical properties. The substrate material was chosen based on the difference in the refractive indices of BTO and MgO. The growth was carried out by pulsed laser deposition (PLD). The crystal structure and epitaxial relations in the grown heterostructures were monitored in situ during growth using high-energy electron diffraction. To study the dependence of the BTO layer polarization on the external electric field, test samples with a buffer conducting layer of SrRuO3 and gold contacts deposited on top were grown. Measurements of the electrophysical properties were performed using a two-probe mode.