Substrate Effects on the Structure and Optical Properties of Epitaxial PbTiO3 Thin Films Prepared by Metal-Organic Chemical Vapor Deposition

Abstract

AbstractEpitaxial PbTiOM3 films were prepared by metal-organic chemical vapor deposition (MOCVD) on MgO(001), SrTiO3 (001) and LaAlO3 (001) surfaces. Four-circle X-ray diffraction and optical waveguiding experiments were performed to characterize the deposited films. The films on all three substrates were single-crystal; however, the domain structure of the films was strongly dependent on the substrate material. Films on MgO and LaAlO3 substrates showed a large amount of 90° domain structures, whereas, the degree of twinning was greatly suppressed for films on SrTiO3. The refractive indices and optical birefringence of the films were measured as a function of wavelength using the film-prism coupling method. We found that for films on LaAlO3 (001), the ordinary index and for films on MgO(001) both the ordinary and extraordinary refractive indices were higher than those of bulk single-crystal PbTiO3. For films grown on SrTiO3 (001), the ordinary refractive index was very close to that of single crystal PbTiO3. We correlate the increased refractive index and the reduced birefringence to the degree of epitaxial strain and twinning in the samples, respectively.