[19p-234B-1~19] 6.4 Thin films and New materials

▲ [19p-234B-1] Structure and optical properties of sputter deposited pseudobrookite Fe₂TiO₅ thin films

〇HaiDang NGO^1,2, Thien Duc NGO¹, Kai CHEN^1,3, Akemi TAMANAI¹, Orjan S. HANDEGARD^1,2, Naoto UMEZAWA¹, Toshihide NABATAME¹, Tadaaki NAGAO^1,2 (1.MANA, NIMS, 2.Hokkaido Univ, 3.Jinan Univ, China)

Keywords:Iron (III) Titanate, pseudobrookite, RF magnetron sputtering, DFT calculation, optical properties

Iron (III) titanates are composed of earth abundant elements and are attracting rapidly growing interest as highly promising candidates for the solar-energy applications such as photo degradation, solar-water splitting, and photovoltaics. In this article, we report a successful synthesis of orthorhombic pseudobrookite Fe₂TiO₅ thin films with RF sputtering followed by post deposition annealing in air at 550^oC. Chemical composition, crystal structure, surface morphology, and optical properties of the synthesized films were experimentally as well as theoretically characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM), Raman scattering spectroscopy, and UV-Vis absorption and DFT simulation. The film was confirmed to be single phase, and exhibited high-crystallinity orthorhombic pseudobrookite structure with a preferential crystal orientation of (131) with excellent adhesion on both glass and silicon substrates. Comparison of dielectric functions between spectroscopic ellipsometry and DFT simulation showed good matching. Estimated direct and indirect band gap values from the optical characterization also well understood in comparison with the energy band diagram from DFT simulations.