Preparation And Properties Of Barium Titanate Perovskite Structure Thin Films

Barium titanate (BaTiO3) thin films have been becoming one of the highlights in the research on functional materials and devices for their potential applications in many fields. Most important of all is the combination of barium titanate thin films with semiconductor integrated technique, and according to their effects of ferroelectric, piezoelectric, thermoelectric, dielectric, electro-optic and non-linear optical to realize their functions in signal memory, transition, modulation, switch, sensor and et al. For the effects of dimension and surface, the lattice structure, chemical states and the electronic states in the film surface (interface) have greatly affected the properties of the films and the practical applies in industries. In this dissertation, the preparation, microstructure physics and properties of barium titanate thin films and doped barium titanate thin flilms by sol-gel process have been presented. The main work is as the follows:1.Perovskite BaTiO3 thin films are grown on SiO2/Si(111) substrates by sol-gel process and rapid thermal annealing (RTA) technique. Surface states and the topmost surface atoms of the BaTiO3 thin films have been analyzed by X-ray photoelectron spectroscopy (XPS) and angle-resolved X-ray photoelectron spectroscopy (ARXPS). The results show that the as-grown BaTiO3 thin films have an enriched-BaO nonstoichiometric surface layer which can be removed by Ar+ ion sputtering, and the atomic ratio of Ba to Ti decreases with increasing the depth of Ar+ ion sputtering.2.The optical transmission spectra of BaTiO3 thin films annealed at different temperatures on fused quartz substrates are measured. The bandgap energies calculated from their optical transmission spectra are larger than that of single crystals reported in the literatures, whereas for poor-crystallized films with lower annealing temperature, their bandgap energy values are much larger than that of single crystals. The large shift...