Effect of cobalt substitution on the optical properties of bismuth ferrite thin films |
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Affiliation: | 1. Frontier Research Academy for Young Researchers, Kyushu Institute of Technology, Iizuka, Fukuoka 820-8502, Japan;2. Physics Department, Miranda House, University of Delhi, Delhi 110007, India;3. Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India |
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Abstract: | Effect of cobalt substitution on the band gap and absorption coefficient of the BiFeO3 thin films formed on quartz substrate by low cost spin coating method have been investigated. BiFe1?xCoxO3 (x=0, 0.03, 0.06 and 0.10) thin films are polycrystalline and it retains the rhombohedral distorted perovskite structure up to 10 mole % of Co substitution. Smooth and compact surface morphology with uniform size particles are observed in SEM micrographs. Narrowing and broadening of band gap is observed as a function of Co content. Two strong emission peaks at ~2.51 eV and ~2.38 eV are recorded for all films with noticeable change in intensity. Results obtained from the optical absorption and photoluminescence spectroscopy experiments have shown that there exists an inverse correlation between the variation in the band gap and the concentration of oxygen vacancies. Band gap decreased by ~100 meV and absorption coefficient increased by 28% at the wavelength of 375 nm in 6 mole % Co substituted thin film and these observations are necessary requirements to improve the efficiency of photovoltaic devices. |
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Keywords: | Optical materials Spin coating method Ferroelectrics Solar energy material |
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