Temperature effect on structural and optoelectronic properties of Bi 2 S 3 nanocrystalline thin films deposited by spray pyrolysis method M. Madoun a , R. Baghdad a,n , K. Chebbah a , M.A. Bezzerrouk a , L. Michez b , N. Benramdane c a Laboratoire de Génie Physique, Université Ibn-Khaldoun, 14000 Tiaret, Algeria b CINaM, UPR3118 CNRS, Campus de Luminy case 913,13288 Marseille cedex 9, France c Laboratoire d'Elaboration et de Caractérisation des Matériaux, Département d'Electronique, Université Djillali Liabes, BP89, Sidi Bel Abbés 22000, Algeria article info Keywords: Bismuth sulfide Spay pyrolysis Nanocrystalline thin films Slater model abstract Bismuth sulfide (Bi 2 S 3 ) nanocrystalline thin films exhibit a low band gap, a high absorbance coefficient and good dispersity. In this study, the structural, optical and electrical properties of Bi 2 S 3 nanocrystalline thin films prepared from bismuth chloride (BiCl 3 ) and thiourea (CS(NH 2 ) 2 ) solutions and deposited by a spray pyrolysis method, are investigated as a function of the substrate temperature (T S ). T S has been increased from 140 to 280 1C by step of 40 1C. Characterizations of the films have been carried out using X-ray diffraction (XRD), scanning electron microscopy, ultra-violet–visible–near infrared (UV–vis–NIR) spectroscopy and electrical resistivity measurements. These studies reveal that Bi 2 S 3 films consist of nanocrystalline grains. Average grain size was calculated using Debye–Scherrer formula. As T S increases, the grain size of Bi 2 S 3 crystallites increases from 40 to 60 nm. In addition, a blue shift of 0.20 eV in the optical band gap energy E g , which is in agreement with Slater's model, and a decrease in electrical resistivity from 2.61 to 1.05 Ω cm was observed. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Semiconductor nanostructured thin films are always important in materials science due to their outstanding electronic and optical properties and useful applications in various optoelectronic devices [1,2]. Bismuth sulfide (Bi 2 S 3 ) is a group V–VI semiconductor that draws much attention for its superior properties such as a high absorp- tion coefficient, a direct band gap energy of 1.2–1.7 eV and a good chemical stability [3,4]. A variety of deposition techniques has been used to grow Bi 2 S 3 nanocrystalline thin films with desirable struc- tural, optical, and electrical properties [5–10]. Every tech- nique has its own advantages and disadvantages. One of the greatest disadvantages is that some of them require very sophisticated instruments along with vacuum facil- ities, which increases the production cost of the material. On the other hand, the chemical spray pyrolysis technique (SPT) is particularly attractive because of its simplicity and has been, during the last decade, one of the major techniques used for the deposition of a wide variety of materials in nanocrystalline thin films. The prime requisite for obtaining good quality nanocrystalline thin films is the optimization of the preparative conditions viz. substrate temperature, spray rate, concentration of solution etc. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/mssp Materials Science in Semiconductor Processing 1369-8001/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mssp.2013.04.004 n Corresponding author. Tel.: +213 7 99 29 94 55; fax: +213 46 42 47 10. E-mail addresses: r_baghdad@univ-tiaret.dz, baghdadrachid@gmail.com (R. Baghdad). Materials Science in Semiconductor Processing ] (]]]]) ]]]–]]] Please cite this article as: M. Madoun, et al., Temperature effect on structural and optoelectronic properties of Bi 2 S 3 nanocrystalline thin films deposited by spray pyrolysis method, Materials Science in Semiconductor Processing (2013), http: //dx.doi.org/10.1016/j.mssp.2013.04.004i