Temperature dependence of optical properties on BaTiO < inf > 3 < /inf > thin films for optoelectronics applications

Abstract

Barium titanate nano particles were synthesized by the wet chemical method using the starting materials barium chloride (BaCl2), titanium dioxide (TiO2) and oxalic acid with different calcinations temperatures. The prepared nano particles were thermally grown onto well cleaned glass substrates under the vacuum of 10-5 torr, using 12A4 Hind Hivac coating unit. The thickness of the film was measured by quartz crystal monitor. The composition of nanoparticles and thin films were identified by EDS spectrum. From X-ray analysis, it has been found that BaTiO3 nanoparticles possess tetragonal structure and the deposited films were polycrystalline in nature, whereas the crytstallinity increases with increase of annealing temperature. Absorption coefficient, extinction coefficient, optical band gap and refractive index of films were estimated from optical transmittance spectrum. The extinction coefficient and refractive index of the BaTiO3 thin films increases with increasing annealing temperature. The optical band gap energy value decreases with increase of annealing temperature.