Cryst. Res. Technol. 46, No. 3, 267 – 271 (2011) / DOI 10.1002/crat.201000549 © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Synthesis and characterization of manganese sulphide thin films deposited by spray pyrolysis M. R. I. Chowdhury 1 , J. Podder* 1 , and A. B. M. O. Islam 2 1 Department of Physics, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh 2 Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh Received 27 October 2010, revised 5 January 2010, accepted 8 January 2011 Published online 21 January 2011 Key words spray pyrolysis, manganese sulfide, thin film, amorphous materials, optical properties, surface properties. Manganese sulphide (MnS) thin films have been deposited onto glass substrate by a low cost spray-pyrolysis technique at 220 °C. The as-deposited MnS thin films have been characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), X-ray diffraction, UV visible spectroscopy and photo electrochemical (PEC) measurement. The SEM and AFM images showed that the MnS thin films were well covered onto the substrate surface. The as-deposited raw thin film was found to be amorphous in nature and perfectly crystalline phase after annealing the sample. Optical band gap of the MnS thin films was found to vary from 3.1 to 3.21 eV and the band gap decreases with the increase in film thickness. Optical constants such as refractive index, extinction coefficient have been evaluated using reflectance and absorbance data. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction During the past few decades, manganese chalcogenides (MnS, MnSe, MnTe, etc.) have given much interest concerning to their structural, chemical and physical properties [1-3]. Among these manganese compounds, MnS belongs to the family of diluted magnetic semiconductor (DMS) and has been extensively studied because of outstanding magneto-optical properties. In DMS, the band electrons and holes strongly interact with the localized magnetic moments and cause a variety of interesting phenomena [4]. The MnS is a wide band gap (E g = 3.1 eV) magnetic semiconductor material having potential applications in solar cell as window/buffer material, solar selective coatings, short wavelength optoelectronic materials, sensors, photoconductors, optical mass memories and storage [5-9]. It is known that the MnS has three crystalline forms: thermodynamically stable α-MnS phase with an octahedrally coordinated rock salt structure, pink metastable tetrahedrally coordinated β and γ-MnS with zincblende and wurtzite structures respectively [10]. It has been found that β and γ-MnS can transform irreversibly to the stable α-MnS in the range of 373 to 673 K [11,12]. Various methods so far adopted for the preparation of MnS thin films, such as molecular-beam epitaxy (MBE) [13], thermal vacuum evaporation [4,10], radio frequency sputtering [14,15], microwave irradiation [16], chemical bath deposition (CBD) [5,9,17], SILAR method [18] and solvothermal method [19]. However, there are no previous reports available on the preparation of MnS thin films by spray pyrolysis method. The high production cost of the conventional solar cells requires a cheaper method to deposit materials for solar energy conversion. Among the all other techniques, the spray pyrolysis is a simple and inexpensive method which does not require any sophisticated instruments like vacuum system, and widely used to produce large area thin films [20,21]. In view of all these aspects an attempt has been made to synthesis MnS thin films at 220 °C by spray pyrolysis from an aqueous medium. The possible chemical reaction that takes place in the growth mechanism of MnS thin film is presented here. The as-deposited MnS thin films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), UV-visible spectroscopy and Photo electrochemical (PEC) measurements. ____________________ * Corresponding author: e-mail: jpodder@phy.buet.ac.bd