Identification of LiNbO3, LiNb3O8 and Li3NbO4 phases in thin films synthesized with different deposition techniques by means of XRD and Raman spectroscopy

Phase composition of epitaxial/textured LiNbO3 films on sapphire substrates, grown by pulsed laser deposition, atmospheric pressure metal organic chemical vapor deposition and pulsed injection metal organic chemical vapor deposition was studied by conventional x-ray diffraction techniques. Raman spectroscopy, being highly sensitive to the symmetry of materials, was used as a countercheck in the compositional analysis. The wavenumbers of Raman modes of LiNb3O8 and Li3NbO4 phases were identified from Raman spectra of synthesized powders. Asymmetry of profiles of x-ray diffraction reflections of LiNbO3 films was studied. This asymmetry may have different origins which consequently may result in misleading conclusions about phase composition of textured LiNbO3 films.