Thickness and substrate effects of epitaxial PbTiO3 thin films

Abstract

Ferroelectric PbTiO3 thin films were epitaxially grown on LaAlO3, and SrTiO3 single crystal substrates by metalorganic chemical vapor deposition and investigated by x-ray diffraction and x-ray photoelectron spectroscopy. The as-deposited films showed clearly thickness and substrate dependence. The thin films on LaAlO3 displayed 90° alternating a-c domain configurations and the a-domain population decreases with decreasing film thickness. The thin films on SrTiO3 were epitaxial and single-domain. Non-stoichiometric surface layer with lead abundance were observed in the 700 Å-thick PbTiO3 films on both LaAlO3 and SrTiO3 substrates, and there might be oxygen vacancy at the surface of 700 Å PbTiO3 films on SrTiO3. Decrease of tetragonal distortion were found with decreasing film thickness, which may indicate weakening of ferroelectricity in the PbTiO3 thin films as compared with bulk material or thicker films.