Multi-technique analysis of MOCVD-grown lead lanthanum titanate (Pb1-xLax)TiO3 thin films on quartz substrates

Abstract

A series of Lead lanthanum titanate (Pb1-xLax)TiO3 thin films with different compositions of x = 0 - 0.33 have been grown on fused quartz substrates by metallorganic chemical vapor deposition (MOCVD) and analyzed by a variety of techniques including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman scattering spectroscopy (RSS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques. XPS results confirmed the film composition of (Pb1-xLax)TiO3 and lanthanum enrichment in top surface layers. XRD indicates a preferred (100) orientation for the films with x values of 0.05-0.17, while the films with x values above 0.32 have randomly distributed orientations. A gradual change in the crystal structure from tetragonal to cubic arrangement with increasing La composition is noted. XPS data also show the variation of Ti-O, Pb-O and La-O bonding with the change in the La composition. The stretching vibrations corresponding to these oxygen related bonding are observed by DRIFT at 667, 826, 936 and 529 cm-1 respectively. This combined investigation on epitaxial PLT films may enhance our understanding of the ferroelectric PLT materials.