Photoluminescence properties of BaMoO4 amorphous thin films

BaMoO4 amorphous and crystalline thin films were prepared from polymeric precursors. The BaMoO4 was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by FTIR reflectance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and optical reflectance, The bond Mo-O present in BaMoO4 was confirmed by FTIR reflectance spectra. XRD characterization showed that thin films heat-treated at 600 and 200 degrees C presented the scheelite-type crystalline phase and amorphous, respectively. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 200 and 600 degrees C. The reflectivity spectra showed two hands. positioned at 3.38 and 4.37eV that were attributed to the excitonic state of Ba2- and electronic transitions within MoO42-, respectively. The optical band gaps of BaMoO4 were 3.38 and 2.19 eV, for crystalline (600 degrees C.2 h) and amorphous (200 degrees C.8 h) films, respectively. The room-temperature luminescence spectra revealed an intense single-emission hand in the visible region. The PL intensity of these materials was increased upon heat-treatment. The excellent optical properties observed for BaMoO4 amorphous thin films Suggested that this material is a highly promising candidate for photoluminescent applications. (c) 2005 Elsevier Inc. All rights reserved.