Structural properties of LiNbO3 thin films grown by the pulsed laser deposition technique

LiNbO3 thin films have been deposited onto R-cut and C-cut single crystalline sapphire substrates (α-Al2O3, (1102) and (0001)) by the pulsed laser deposition technique at different oxygen pressures and substrate temperatures. Thin film composition and structure have been determined using Rutherford backscattering spectroscopy (RBS) and X-ray diffraction experiments. The atomic composition is dependent on the oxygen pressure in the range 0.5–1.3 mbar. At pressures lower than 1.3 mbar, we have observed a deviation from the stoichiometry. Nearly stoichiometric thin films have been obtained for a pressure equal to 1.3 mbar. For that pressure, the atomic composition does not depend on the substrate temperature in the range 650–800°C. Under optimised conditions the 〈1102〉 and 〈0001〉 preferential orientations of growth have been obtained on (1102) and (0001) sapphire substrates, respectively.