The microstructure dependence on processing temperature in sol-gel derivedthin ferroelectric films of LiNbO3 on SiO2/Si substrate

In this paper, we report our sol-gel derived thin films of LiNbO3 on silica -on-silicon, a potential substrate for integrated optics. The dependence of the microstructure of these films on the processing temperature is present ed. The films are studied by means of X-ray diffraction, atomic force micro scopy, Raman spectroscopy, and variable angle spectroscopic ellipsometry. W e find that the smoothness of the films can be improved by continuously ann ealing the films in several steps. The experimental results show that the 5 00 degrees C annealed films have a nanocrystalline nature with the grain si ze ranging from 39nm to 109nm. The ultrafine crystalline structure and the pure trigonal phase of the film material make it suitable for E-O and A-O w aveguide applications.