Structural and optical properties of Fe doped bismuth titanate thin film deposited by RF sputtering

Abstract

Achieving wide band gap tunability in complex oxide materials is highly desirable for the development of current materials research and photovoltaic device applications. To tune the band gap of complex oxides, ferroelectric iron doped BLT thin films (BLFT) were fabricated on SrTiO3 substrates by RF sputtering at various growth temperatures. The structural and optical properties were analyzed by X-ray diffraction, scanning electron microscopy, and ultraviolet-visible absorption spectroscopy. As the growth temperature was increased from 500 to 800 degrees C, the crystallinity of the BLFT thin films was enhanced by the smooth surfaces, whereas the optical band gap was increased from 2.69 to 2.75 eV. On the other hand, the optimized deposition temperature of the BLFT film was 750 degrees C because of the almost complete crystalline phase. This result was found to be sensitive to the deposition temperature when the BLFT epitaxial thin-films were prepared by RF sputtering for the band-gap narrowing. (C) 2016 The Japan Society of Applied Physics