Substrate temperature effect on the optical properties of amorphous Sb2S3 thin films

Abstract

Sb 2 S 3 amorphous thin films were prepared by thermal evaporation of corresponding powder on thoroughly cleaned glass substrates held at temperature in the range 300-473 K. X-ray diffraction and atomic force microscopy have been used to order to identify the structure and morphology of surface thin films. The optical constants of the deposition films were obtained from the analysis of the experimental recorded transmission data over the wavelength range 400-1400 nm. An analysis of the absorption coefficient values revealed an optical indirect transition with the estimation of the corresponding band gap values. It was found that the optical band gap energy decrease with substrate temperature from 1.67 eV at 300 K to 1.48 eV at 473K.

The electronic structure of the antimony chalcogenide series: Prospects for optoelectronic applications

“…Band structure calculations for Sb 2 S 3 using PBE-DFT show that it posses an indirect fundamental band gap of 1.35 eV with the valence band maximum and conduction band minimum located at G and Y, respectively [32]. Sb 2 S 3 has a direct optical band gap with experimental studies reporting a range from 1.66-2.24 eV [14,32,33,34,35,36,37,38,39,40,41], which is found to increase with the film thickness and temperature [42,43]. The nature of the band gap for Sb 2 Se 3 is also unclear but an experimental range of 1.00-1.82 eV has been reported, where the lower energy transitions are considered to be indirect [44,45,46,47].…”

STRUCTURAL CHARACTERIZATION AND ELECTRICAL PROPERTIES OF a- S/Sb RATIO THIN FILMS.

“…Since, the DTA analysis gives the glass transition temperature (T a ) and the crystallization temperature (T c ) equal to 490 and 520K, respectively. The main phase of this figure represents Sb 2 S 3 thin films as the same [12,13], shown in Table 1. The mean coordination number, Z, is between 2.1 and 2.4 because Sb has three-fold coordinates and S has two-fold coordinates.…”

“…Many workers were obtained Sb 2 S 3 thin films by various sophisticated techniques such as electro-deposition [5], dip-dry technique [6], spray pyrolysis [7], chemical bath deposition [8], successive ionic layer adsorption and reaction (SILAR method) [9], the sol-gel method [10] and vacuum evaporation [11][12][13]. Also, the effect of depositions condition on physical properties of thin films was studied.…”

Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra

“…The Pointwise Unconstrained Minimization Approach (PUMA) numerical method (Birgin et al, 1999;Mulato et al, 2000;Erarslan & Gungor, 2010;Ventura et al, 2005) and algebraic methods (Peng & Desu, 1994;Birgin et al, 1999), based on approximate equations derived from reasonable assumptions, were widely used to extract spectral dispersion of optical constants of a film and its geometric thickness from normal-incidence -and/or -spectra of its air-supported {thin film/thick substrate}-stack, both of which do not require in prior a dispersion functional model. An algebraic method in this category is the envelope method, developed and refined by a number of authors ( Manifacier et al, 1976;Swanepoel, 1983;Minkov, 1990;El-Naggar et al, 2009;Epstein et al, 1987;González-Leal et al, 1998;Tigau, 2006;Poelman & Smet, 2003), whose viability is based on the presence of many interference-fringe maxima and minima on transmittance (reflectance) spectra in transparent and weak absorption regions of the film, and cannot be applied to spectra displaying few interference fringes. This is not a problem in optical analysis based on PUMA program or curve-fitting softwares that can be used to analyze transmittance and reflectance spectra of multi-layered structures, irrespective of the number of observed interference-fringe extrema.…”

“…Only when a global minimum solution for the curve-fitting problem is achieved, one obtains reliable and informative dielectric and optical parameters for the studied film. If the substrate in the {air/thin uniform film/thick substrate/air}-stacking is transparent ( ≅ 0) in the spectral region above the absorption edge of the film, the -formula given in Equation (4) reduces to a wieldy expression that forms the basis of the analytical envelope and PUMA methods (Birgin et al, 1999;Mulato et al, 2000;Erarslan & Gungor, 2010;Ventura et al, 2005;Manifacier et al, 1976;Swanepoel, 1983;Minkov, 1990;El-Naggar et al, 2009;Epstein et al, 1987;González-Leal et al, 1998;Tigau, 2006;Poelman & Smet, 2003;Swanepoel, 1984;Chambouleyron & Martínez, 2001;Truong & Tanemura, 2006;Kasap & Capper, 2006), the application of which do not necessitate in prior dispersion functions for the film's optical constants.…”