Epitaxial LiNbO3 films were deposited on (00•1) Al2O3 substrates by pulsed laser deposition. The microstructure of the samples was investigated by X-ray diffraction reciprocal space mapping. Data acquisition was performed on a high-resolution set-up suited to the study of oxide materials. The (00•k) planes of the layer were found parallel to the (00•k) planes of the substrate. The large in-plane misfit gave rise to 2 in-plane orientations. In the direction perpendicular to the surface the crystallite size (163nm) was much smaller than the film thickness (510nm) suggesting the presence of planar defects. Moreover, the values of the mosaicity (1.2°) and root-mean-square strain (0.17%) could not be solely explained by misfit dislocations. Conversely the high-thermal expansion coefficient mismatch was at the origin of a high compressive strain level (-0.18%) and may also be responsible for the large column length distribution, root-mean-square strain and mosaicity.

Defect Structure of Pulsed Laser Deposited LiNbO3/Al2O3 Layers Determined by X-ray Diffraction Reciprocal Space Mapping. A.Boulle, L.Canale, R.Guinebretière, C.G.Bin, A.Dauger: Thin Solid Films, 2003, 429[1-2], 55-62