Preparation of C-axis textured LiNbO3 thin films on SiO2/Si substrates with a ZnO buffer layer by pulsed laser deposition process

Highly C-axis textured LiNbO3 thin films were grown on SiO2/Si substrates with a ZnO buffer layer by XeCl excimer pulsed laser deposition technique. We fixed the target–substrate spacing at 40 mm, oxygen flow rate of 20 sccm and the repetition rate of 5 Hz, and then changed the substrate temperature, energy density and oxygen pressure to obtain the optimum deposition conditions. The effect of post-annealing process on improving the structural properties of the as-deposited LiNbO3 thin films was also studied. The ZnO buffer layers and LiNbO3 films were characterized by X-ray diffraction (XRD), atomic force microscopy and scanning electron microscopy to analyze their crystalline structure, surface roughness and surface morphology, respectively.For the optimum deposition parameters such as substrate temperature of 700 °C, energy density of 4.6 J/cm2 and oxygen pressure of 150 Pa, the full width at half maximum intensity (FWHM) of LiNbO3(0 0 6) peak was 0.22°. The FWHM of LiNbO3(0 0 6) peak was further reduced to 0.19° via. in-situ post-treatment at 750 °C for 30 min. The results could be useful for integrating the surface acoustic wave device, optical waveguide and semiconductor device on the same Si substrate.