Synthesis and characterization of (111)-oriented BaTiO3 thin films

The synthesis of (111)-oriented BaTiO3 thin films on Nb-doped SrTiO3 and bilayers of BaTiO3 and La0.7Sr0.3MnO3 on SrTiO3 are investigated. With increasing thickness the films are found to exhibit a decreasing out-of-plane lattice parameter and increased surface roughness. The BaTiO3 films on doped SrTiO3 are found to be relaxed with indications of increasing defect density with increasing thickness. Through piezoresponse force microscopy, pyroelectric measurements, and tunneling electroresistance measurements, indications of ferroelectric behavior are found in (111)-oriented BaTiO3 down to a thickness of 5 nm.