STRUCTURAL AND MICROSTRUCTURAL EVOLUTION OF BARIUM-TITANATE THIN-FILMS DEPOSITED BY THE SOL-GEL PROCESS

Barium titanate thin films were fabricated by the sol-gel technique from two different precursors, one using barium 2-ethyl haxanoate and other using barium hydroxide dissolved in methoxy ethanol as barium source. The films were examined at different curing temperatures using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, optical transmission spectroscopy, and x-ray diffraction. The films prepared from an ethyl hexanoate precursor were found to crystallize around 550-degrees-C into tetragonal polycrystalline form, whereas those prepared from a barium hydroxide precursor were crystallized into cubic form around 600-degrees-C. The films prepared from the ethyl hexanoate precursor showed larger shrinkage during heat treatment and were more porous than those made from the hydroxide precursor. The changes in thickness, refractive index, and band gap of the films annealed at different temperatures were correlated with chemical modifications of the precursor film as well as structural and microstructural changes occurring during the formation of the final barium titanate thin film. FTIR spectroscopy and electron microscopy were used to support these observations.