Thin films of LiNbO₃ prepared on SiO₂/Si by sol-gel processing for active SOS device applications

Thin films of lithium niobate are derived on SiO₂/Si substrate by the sol-gel method. The solution is prepared by mixing LiOC₂H₅ and Nb(OC₂H₅)₅. The films are deposited by spin coating and are annealed at different temperatures of 400 °C, 500 °C, 600 °C and 700 °C. The films are characterized by means of X-ray diffraction, atomic force microscopy and variable: angle spectrosopic ellipsometry. The experimental results show that when the heat treatment temperature is about 500 °C, the films starts to crystallize and the desirable ferroelectric phase dominates. The crystalline size of the 500 °C annealed film ranges from 39nm to 86nm and the film is microscopically continuous and uniform. The refractive index of the film found to be 1.83 at the wavelength of 633nm. The nanocrystalline nature, the ferroelectric phase and the refractive index of the films make them potential candidates for active integrated optical component applications.