Lithium niobate thick films grown by RF sputtering: Correlation between optical analysis and transmission electron microscopy observations

We report on the low temperature process for depositing epitaxial LiNbO3 (0 001) thick films on sapphire (0001) substrates by radio-frequency magnetron sputtering. To obtain this objective, we have developed a multi-steps proc ess. Structural studies carried out through x-ray theta -2 theta and phi sc ans measurements revealed that the epitaxy is verified at a substrate tempe rature of 490 degreesC whatever the film thickness. The crystalline propert ies and the surface morphologies are rather conserved in the multi steps pr ocess of deposition. Optical prism coupling characterizations have been car ried out to qualify the film and the interface between the film and the sub strate. A discussion is proposed in relationship with transmission electron microscopy (TEM) analysis.