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This study concerns structural and optothermal properties of iron ditelluride layered structures which were fabricated via a low-cost protocol. The main precursors were FeCl3·6H2O and Fe2O3. After a heat treatment within a tellurium-rich medium at various temperatures (470°C, 500°C, and 530°C) during 24 h, classical analyses have been applied to the iron ditelluride layered structures. A good crystalline state with a preferential orientation of the crystallites along (111) direction has been recorded. Moreover, additional opto-thermal investigation and analyses within the framework of the Lattice Compatibility Theory gave plausible explanation for prompt temperature-dependent incorporation of tellurium element inside hematite elaborated matrices. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the structural properties of FeTe2 thin films obtained using a simple and non-toxic experimental procedure. First, iron oxide thin films have been prepared by the spray pyrolysis technique from an aqueous solution containing FeCl3 6H2O (0.03M) as a precursor onto glass substrates heated at 623K. Second, these films were subjected to a heat treatment under tellurium atmosphere at various temperatures (723–803K) for 24h. XRD analysis revealed that FeTe2-ortorombic phase films were obtained at a heat treatment of the order of 773K. This film has a good crystalline state with a preferential orientation of the crystallites along (111) direction. Moreover, AFM as well as SEM morphological observations show a relatively perturbed surface state. To date, this simple and low cost route process to obtained FeTe2 thin films has not yet been used. [Copyright &y& Elsevier]

Abstract: Cu2SnS3 thin film have been synthesized by solid state reaction under vapour sulphur pressure at 530 °C, during 6 h, via a sequentially deposited copper and tin layers Cu/Sn/Cu…Sn/Cu/Sn. The structure and the composition were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA). X-ray diffraction revealed that as the deposited film crystallizes in the cubic structure and the crystallites exhibit preferential 111 orientation of the grains. Moreover, EPMA analysis confirmed that the obtained film is stoichiometric. The SEM study shows the presence of spherical particles of ≈100–120 nm diameters. The optical absorption coefficient and band gap of the film were estimated by means of transmission and reflection optical measurements at room temperature. A relatively high absorption coefficient in the range of 104 cm−1 was indeed obtained and the band gap value is of the order of 1.1 eV. On the other hand, the electrical conductivity of Cu2SnS3 film prepared in the present experiment is suitable for fabricating a thin film solar cell based on not cheaper and environmental friendly material. [Copyright &y& Elsevier]

Abstract: Sb x O y oxides thin films have been prepared on glass substrates by a heat treatment of Sb thermal evaporated thin films in air atmosphere. X-ray diffraction analysis shows that the films annealed at Tr=550°C are well constituted of the Sb2O4 orthorhombic phase with elements oriented preferentially towards (004) direction. In the same way, from the optical transmission T(λ) and reflection R(λ) curves, the study of the absorption coefficient of these films versus incident energy revealed that the value of the band gap energy of Sb2O4 oxide is of the order of 3.9eV. Mechanical and opto-thermal original investigations confirmed the annealing temperature-related enhancement of the fabricated layers. [Copyright &y& Elsevier]

Abstract: In2S3 thin films have been synthesized by annealing indium thin films under sulfur pressure. The indium thin films have been deposited by evaporation onto glass substrates. The sample is then introduced, with small grains of sulfur into a Pyrex tube. The latter is sealed under vacuum and then annealed for two hours at temperatures ranging from 280 ∘C to 400 ∘C in a step of 40 ∘C.This simple and economic technique allows the elaboration of In2S3 thin films crystallized in the structure. Optical density (O.D.) measurements were made for In2S3 thin films synthesized at different temperatures. The optical spectra show that the threshold value of optical absorption is approximately 610 nm. By increasing the synthesis temperature this threshold value moved towards higher wavelength values. The gap is around 3 eV and the electrical resistivity measurements at room temperature, show that the films are highly resistive with an electric conductivity around 10−1 (Ωcm)−1. [Copyright &y& Elsevier]

Abstract: The present work was aimed on utilizing the solid state microwave synthetic method for the growth of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) in powder as well as in the form of thin films. It was observed that the microwave exposure of simple powder mixture of Mo (or W) and S could not lead to the formation of MoS2 (or WS2). Therefore the work was pursued by the study of the possibility to use this technique to grow thin films. Either Mo or W in the form of thin foils or Mo layers deposited by sputtering onto glass substrates was used as metal source. These metal samples were introduced with some sulphur into a Pyrex tube and sealed under vacuum. After microwave oven exposure the formation of polycrystalline 2H-WS2 with well-defined grains was confirmed by X-ray diffraction and scanning electron microscopy, respectively. Mo foil as well as Mo layers deposited on glass showed formation of MoS2 under the limit of our experimental conditions that is to say homogeneous thin films can be achieved only as small surface films. [Copyright &y& Elsevier]

Abstract: We report in this work the optical and structural properties of iron diselenide films (FeSe2) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe2 as well as FeSe2−x phases begin to appear at a selenization temperature of 500 °C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe2 phase. At 550 °C, a single FeSe2 phase having good crystallinity was obtained. At 600 °C, two phases were detected: the major one corresponds to Fe3O4, and the minor one to FeSe2. SEM surface views show that FeSe2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe2 films were found, respectively, at 550 °C and 600 °C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe2 phase and to a Fe-rich non-stoichiometric phase, respectively. [Copyright &y& Elsevier]

Abstract: Thin layers of copper indium disulphide were prepared on Pyrex glass substrate at 320°C by the chemical reactive spray process from an aqueous solution containing cuprous and indium chlorides, and thiourea. Films bulk and surface were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to understand the effect of layers microstructure on their optical properties. In the present study, we attempted to interpret the reflectance and transmittance of sprayed CuInS2 films. We showed that the optical spectral profiles of such material are highly related to the optical scattering of light. Indeed, by taking into account the surface roughness and assuming the layer as an effective medium composed of CuInS2 crystallites with gaseous inclusions, we have practically reproduced R(λ) and T(λ) spectra. [Copyright &y& Elsevier]

Abstract: FeS2-thin films with good crystallinity were synthesized by a simple method which consists of sulphuration, under vacuum, of amorphous iron oxide thin films pre-deposited by spray pyrolysis of FeCl3·6H2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C. At optimum sulphuration temperature (450 °C) and duration (6 h), black green layers having granular structure and high absorption coefficient (∼5.104 cm−1) were obtained. The study of the electrical properties of the as-prepared films vs. the temperature variations showed three temperature domain dependence of the conductivity behaviour. The first one corresponds to the high temperature range (330 K–550 K) for which an Arrhenius plot type was obtained. The activation energy value was estimated at about 61.47 meV. The second domain corresponding to the intermediate temperature range (80 K–330 K) showed a variable activation energy between the grain boundaries. The barrier height, qϕ¯, was estimated to 27±0.5 meV, and the standard deviation, qσ ϕ , was evaluated at about 14±0.5 meV. We found that at lower temperatures (20 K–80 K), the conductivity is governed by two conduction types. The density of localised states, was about 2.45×1020 eV−1 cm−3. [Copyright &y& Elsevier]

Abstract: The present paper investigates a simple and non-toxic method to transform amorphous iron oxide pre-deposited by spray pyrolysis of FeCl3·6H2O (0.03M)-based aqueous solution onto glass substrates heated at 350°C into FeSe2 thin films. The amorphous iron oxide films were heat treated under a selenium atmosphere (10−4 Pa) at different temperatures for 6h. X-ray diffraction (XRD) was used to investigate the structure of the obtained films. Single FeSe2-phase films having good crystallinity were obtained at a selenisation temperature of 550°C. Optical analyses of the FeSe2 films obtained at 550°C enabled us to deduce a large absorption coefficient (, ). Surface scanning electron microscopy (SEM) observations show inhomogeneous films. Electrical conductivity of the as-prepared films was measured at high and low temperatures. [Copyright &y& Elsevier]

Abstract: Amorphous iron oxide films were prepared by spray pyrolysis of FeCl3·6H2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C. Rust red iron oxide films were obtained. Crystallized iron oxide films were achieved after heat treatments in vacuum. X-ray diffraction (XRD) patterns show two polycrystalline iron oxide phases. The dominant phase corresponds to Fe2O3 and the minor one corresponds to traces of FeOOH, which transforms immediately to Fe2O3 after further heat treatment. Scanning electron microscopy (SEM) microanalyses show that stoichiometric Fe2O3 films were obtained. Sulphuration at 450°C for 6 h under vacuum (10−4 Torr) transforms the amorphous iron oxide films into FeS2-pyrite films having good crystallinity. SEM images show that the FeS2 films are granular. The homogeneity and both dimension and distribution of the FeS2 grain sizes were found to depend on the sulphuration temperature of the pre-deposited amorphous iron oxide films. First optical analyses enabled us to deduce a direct energy band gap of about 0.72 eV. All the prepared FeS2 films show p-type conduction. [Copyright &y& Elsevier]