Iron pyrite thin films synthesized by spray pyrolysis technique (original) (raw)
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Materials Characterization, 2005
FeS 2 -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 FeCl 3 d 6H 2 O (0.03 M)-based aqueous solution onto glass substrates heated at 350 8C. At optimum sulphuration temperature (450 8C) and duration (6 h), black green layers having granular structure and high absorption coefficient (~5.10 4 cm À1 ) were obtained. The study of the electrical properties of the asprepared 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, q/, was estimated to 27F0.5 meV, and the standard deviation, qr / , was evaluated at about 14F0.5 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 2.45Â10 20 eV À1 cm À3 .
Journal of applied sciences and nanotechnology, 2022
In this work, the physical properties of iron sulfide (FeS2) thin films deposited by the chemical spray-pyrolysis (CSP) technique were studied. The thin films are deposited on glass substrates at 200 o C, using FeCl3 salt with thiourea (NH2)2CS as precursors. Structural analysis of X-Ray diffraction manifested that the thin films contain two phases: Marcasite and Pyrite in planes (110), (111) at angles 2θ =26.3°, 2θ =28.3° respectively. Optical properties analysis showed that the prepared iron sulfide thin-films were highly absorbing in the UV-Visible range and the absorption coefficient was in the range of 1.6x10 5 cm-1 with a relatively low resistivity of about 0.49 (Ω.cm). The calculated activation energy (Ea) was 0.024 eV and the bandgap value was 2.45 eV. Moreover, the FeS2 thin films were also deposited on (CdO) to fabricate a heterojunction photocell. In conclusion, there is the feasibility of preparing low-cost and highly absorbing iron sulfide (FeS2) thin films for optoelectronic applications with acceptable homogeneity using the spray-pyrolysis technique.
Korean Journal of Chemical Engineering, 2018
Iron pyrite (FeS 2) thin films were fabricated by spin coating the solution of FeS 2 nanocrystals of ~40 nm in size on glass substrates, followed by annealing in a sulfur environment at different temperatures. The effect of sulfurization temperature on the morphology, structural, optical and electrical properties was investigated. With increase of the sulfurization temperature, the grain size and crystallinity of the films was improved, although some cracks and voids were observed on the surface of thin films. The band gap of the FeS 2 films was decreased at higher sulfurization temperature. The electrical properties were also changed, including the increasing in resistivity and the decrease in Hall mobility, with increase of sulfurization temperature. The change in the optical and electrical properties of the FeS 2 thin films was explained based on the changes of phase, morphology, surface, and grain boundary property.
Iron pyrite films prepared by sulfur vapor transport
Thin Solid Films, 1996
Iron films deposited via thermal evaporation, with a thickness between i00 and 250 nm, were converted into FeS2 by open sulfur transport using nitrogen as a gas vector. The films thus obtained constituted a single pyrite phase and were optically highly absorbing. The sulfurization process was optimized. As a result, sample temperature and conversion time were found to be the major determining parameters. The films were characterized using several methods. The crystallinity and phase identification were determined by X-ray diffractometry. Scanning electron microscopy showed a homogeneous surface of both iron and pyrite layers. Optical transmission measurements confirmed the highly absorbing character of FeS2 and allowed the determination of direct (1.35 eV) and indirect (0.82 eV) transitions.
Comparison of pyrite thin films obtained from Fe and natural pyrite powder
Applied Surface Science, 1991
Pyrite thin films have been prepared by two different procedures: by sulphurating thermally evaporated iron films and by flash evaporating natural FeS 2 powder. The structural, morphological, electrical and optical properties of both kinds of films are compared and the influence of the sulphuration conditions studied. The films directly evaporated from pyrite powder show higher absorption coefficients and better photoactive response than those prepared from iron. Sulphuration of the films is always required in order to improve the crystallinity and decrease the density of sulphur vacancies generated by these methods.
Science Journal of University of Zakho, 2020
Pyrite phase FeS2 thin films have been grown by a two-stage process of chemical bath deposition followed by sulfurization. Thiourea and thioacetamide were used as sulfur precursors in separate baths. The deposition time was controlled for 1, 2, and 3 hours respectively. The as-deposited films were sulfurized at temperatures of 250 o C and 500 o C to form the pyrite phase. The effect of deposition time and sulfurization temperature on the structure, morphology and optical properties of the iron pyrite films obtained from the two separate baths were studied and compared. X-ray diffraction analyses established the formation of the pyrite phase in all the films after sulfurization, in addition to iron (II) oxide hydrate as impurities. All films showed further improvement in pyrite formation, crystallinity as well as an increase in crystallite size after sulfurizing at 500 o C. EDAX and SEM microscopy showed that the iron pyrite films produced from the bath containing thiourea, had better crystallinity and a higher iron content. The optical band gap of the iron pyrite films obtained with thiourea, was 2.1, 1.9 and 1.6 eV for the various deposition times. With thioacetamide, the band gap was 1.4 eV, for the deposition time of 3 hours.
Iron pyrite FeS2 for flexible solar cells
Renewable Energy, 1992
We used the vacuum thermal evaporation technique to grow iron thin films on heated glass substrates. Thick fresh iron layers (1000 3000 A) sulfurized under nitrogen flux were converted into iron pyrite FeS~ phase identified by X-ray study. Reproducible 1 2 kf~ (10-2 f~-cm) FeS2 layers showed P type conductivity. Nevertheless, iron films previously oxidized showed N type behaviour when submitted to the same sulfurization process. Optical transmission measurements had been carried out on several thicknesses before and after layer conversion. The results confirmed the highly absorbing character of the pyrite FeS2 and also the presence, in the explored spectral range (UV-Visible) of two competitive transitions : the first at 1.31 eV (indirect gap) and the second at 1.45 eV (direct gap). Some interpretations are given concerning the origin of the opacity of thc FeS2 obtained from Fe films. Comparison is made with iron pyrite results obtained by spray pyrolysis as reported by some workers.
Preparation and Characterization of Iron Sulphide Thin Films by Chemical Bath Deposition Method
Indonesian Journal of Chemistry
FeS2 thin films have been deposited by using low cost chemical bath deposition technique. The films obtained under deposition parameters such as bath temperature (90 °C), deposition period (90 min), electrolyte concentration (0.15 M) and pH of the reactive mixture (pH 2.5). The thin films were characterized using X-ray diffraction and atomic force microscopy in order to study the structural and morphological properties. The band gap energy, transition type and absorption properties were determined using UV-Vis Spectrophotometer. X-ray diffraction displayed a pattern consistent with the formation of an orthorhombic structure, with a strong (110) preferred orientation. Atomic force microscopy image showed the substrate surface is well covered with irregular grains. A direct band gap of 1.85 eV was obtained according to optical absorption studies. Keywords: Iron sulfide, X-ray diffraction, chemical bath deposition, thin films
Open Journal of Applied Sciences
Single phase iron pyrite (FeS 2 ) films have been successfully deposited on ITO-coated glass substrates using a 3-electrode electrochemical system with graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the FeS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained FeSO 4 •7H 2 O as an iron source, and Na 2 S 2 O 3 •5H 2 O as a sulfur source. The deposition was carried out potentiostatically at a constant potential of −0.9 V vs. Ag/AgCl at room temperature. The growth of the iron pyrite phase was achieved by annealing the as-deposited at 500˚C for an hour in an ambient of sulfur to form the pyrite phase. For sulfurization, two different techniques, one using the Kipp's apparatus and a second, which involved heating elemental sulfur at 200˚C, were used for the production of the sulfur gas. X-ray diffraction analyses of the sulfurized films showed that both sulfurization techniques appeared to form the pyrite phase, however, the second method yielded films with maximum crystalline order and stoichiometry with no discernable impurity peaks. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.75 eV. SEM micrograph showed a compact morphology with a rough surface made up of crystallites of irregular shapes and sizes with well-defined edges, covering the entire substrate. EDAX analysis of the film was consistent with the formation of FeS 2 pyrite thin films.