Chalcogenide Letters Vol. 7, No. 9, September 2010, p. 531 -538 STRUCTURE AND OPTICAL PROPERTIES OF CHEMICALLY DEPOSITED TIN SELENIDE N.A. OKEREKE, A. J. EKPUNOBI a Industrial Physics Department, Anambra State University, Uli, Nigeria a Department of Physics and Industrial Physics, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria Tin selenide (SnSe) thin films have been prepared using chemical bath deposition technique. Deposition at various deposition conditions was studied in order to investigate the effect of these parameters on the film properties. The structural, morphological and optical properties of films were studied by using x – ray diffraction (XRD), optical microscopy (OM) and the spectrophotometer. The films prepared were found to be polycrystalline in nature. XRD studied confirms the formation of orthorhombic selenide structure with the preferred orientation along the (210) plane. The material covered the surface of the substrate completely. The optical band gap was found to be indirect, which was equal to 1.5 eV. (Received September 2, 2010; accepted September 21, 2010) Keywords: Tin selenide, Chemical bath, Structural and optical properties 1. Introduction Tin selenide (SnSe) is one of the IV-VI semiconductors. For over a decade, IV-VI semiconductors have attracted growing interest owing to their important unique properties in optoelectronics such as light emitting diodes or laser diodes (Krause et al, 1994), memory switching devices (Subramanian et al, 1999), and infrared production and detention (Rodat M, 1975). A number of techniques are employed in the formation of high quality thin films such as chemical vapor deposition, molecular beam epitaxy, electrochemical, evaporation and sputtering. (Sankara et al 2003 and Guziewiez et al 2004). However there is an interest to investigate other techniques, which could be new possibilities in terms of device properties, structure. Chemical bath deposition (Wang et al 1999) belongs to these alternative techniques that could also produce high quality films of IV – VI semiconductor materials. It seems to be an inexpensive, simple, low temperature method that could produce good quality films for device application. SnSe is considered as an important technological semiconductor having a potential solar cell material (Rodat, 1977 and Parentau et al 1990). It is a narrow band gap binary IV – VI semiconductor displaying a variety of applications as essential material in photo-electrochemical solar cells to enhance the fill factor in electrical switches and in junction devices (Sugana et al, 1996). SnSe thin film has an indirect band gap of 1.50 eV. In this paper, the structural and optical properties of SnSe thin film prepared by chemical bath deposition method were studied. 2. Experimental details Tin selenide films were deposited onto glass substrates using CBD method at room temperature. The reagents used were tin chlorides (SnCl 2 ) as the source of cation (Sn 2+ ), potassium selenate (K 2 SeO 4 ) as the source of anion (Se 2- ), EDTA the complexing agent which is used to