Structural characterization and optical constants of CuIn3Se5 vacuum and air annealed thin films

Milled powder of ordered defect compound (ODC) CuIn3Se5 phase was successfully synthesized via milling process. Thin films of CuIn3Se5 were deposited onto glass substrates at room temperature by thermal evaporation technique. The obtained layers were annealed in vacuum and air atmosphere. The structural and compositional properties of the powder were analyzed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Powder XRD characterization, Rietveld analysis and chemical bounding confirm the tetragonal ordered defect compound phase formation with lattice constants a = 5.732 angstrom and c 11.575 angstrom. Thin films were characterized by XRD, atomic force microscopy (AFM) and UV/Vis spectroscopy. Transmittance (T) and reflectance (R) spectra were measured in the spectral range of 300-1800 nm. The absorption coefficient a exhibits high values in the visible range and reaches a value, of 10(5) cm(-1). The band gap energy E-g of the annealed thin films is estimated to be approximately 1.75 eV. The refractive index n was estimated from transmittance data using Swanepoel's method. The refractive indices of the films as a function of wavelengths can be fitted with Cauchy dispersion equation. The oscillator energy E-0, dispersion energy E-d, zero frequency refractive index no, high frequency dielectric constant so, and the carrier concentration per effective mass N/m* values were determined from the analysis of the experimental data using Wemple-Di-Domenico and Spitzer-Fan models. We exploited the refractive index dispersion for the determination of the magneto-optical constant V, which characterizes the Faraday rotation. The nonlinear optical parameters namely nonlinear susceptibility chi((3)), nonlinear refractive index and nonlinear absorption coefficient beta are investigated for the first time for CuIn3Se5 material. (C) 2017 Elsevier B.V. All rights reserved.