International Journal of Research and Innovation in Applied Science (IJRIAS)|Volume I, Issue VIII, November 2016|ISSN 2454-6194 www.ijrias.org Page 6 Structural and Optical Characterization of Nanocrystalline SnSe Thin Film Keyur S. Hingarajiya # , K. D. Patel * and G. K. Solanki * # R. G. Shah Science College, Vasna, Ahmedabad-382460, Gujarat,India. * Dept. of Physics, S. P. University, V. V. Nagar-388120, Gujarat,India. Abstract--Structural and optical properties of nanocrystalline SnSe thin film confer in this paper. For that purpose Nanocrystalline thin film of SnSe was deposited at room temperature having thickness 1μm, 2μm, 3μm and 4μm. Structural and optical properties studied by XRD, TEM, AFM, and Uv-Vis- Nir spectroscopy methods of all thin films. From these studied we found there is a strong effect of thickness on structural and optical properties of Nanocrystalline SnSe thin film. Key words: Nanocrystalline, thin film, XRD, AFM I. INTRODUCTION emiconductor nanostructures are of current interest due to the variation of their bulk properties when their characteristic dimensions become smaller than the mean free path of the carriers [1-3]. A key aspect of semiconductors in a nanostructured form is the modification of the energy levels and the density of states owing to the confinement of the charge carriers. The charge carriers are localized in nanostructures and this leads to a blue shift in the band gap [4,5]. Semiconductor nano materials exhibit size-dependent electronic band gap energies [6], melting temperatures [7], soild-solid phase transition temperatures [8] and pressures [9]. These properties of nanocrystals make them an interesting category of materials from photovoltaic, photoelectrochemical, electrochemical and nanoelectronic devices point of view [10-13]. Semiconductor compounds such as tin selenide (SnSe), a narrow band gap semiconductor [14], has attracted a lot of attention [14–22] in the last years due its great technological interest as optical and optoelectronic materials [22,23]. SnSe is widely used as holographic recording systems, infrared electronic and memory switching devices [23,24]. It is also used in photoelectrical cells, decreasing the photocorrosion process [23]. Keeping all these thing in mind, Nanocrystalline thin film of SnSe was deposited by spin coating having thickness 1μm, 2μm, 3μm and 4μm and its structural and optical properties were studied by XRD, TEM, AFM and UV-VIS- NIR spectroscopy methods. II. EXPERIMENTAL Tin salt (SnCl 2 ·2H 2 O), gray selenium powder (Se), ammonia buffer (p H =11), and sodium sulfite (Na 2 So 3 ) were used in our experiments. All chemicals were purchased from ALFA AESAR Company having 99.99% purity. Thin film deposition process was divided in to four steps as discussed below. In the first step SnCl 2 ·2H 2 O was dissolved in double distilled water and ammonia buffer is added drop wise to obtain an alkaline media of p H =11. Sodium selenosulfate, which was used as a source of selenide ions for the purpose of this study, is commercially unavailable substance because it is relatively instable, especially upon exposure to light and it has to be freshly prepared prior to the thin film deposition process. Hence in second step we prepared the solution of sodium selenosulfate by adding gray selenium to a hot solution of sodium sulfite. The resulting heterogeneous solution was stirred for 10h at 373K by magnetic stirrer and afterwards the excess of gray selenium was filtered. The preparation of sodium selenosulfate solution is based on the following redox process. In the third step prepared solution of Sodium selenosulfate and solution of SnCl 2 ·2H 2 O were mixed that results in to precipitation of Nanocrystalline SnSe formed in mixed solution by following the reaction, The chemical deposition of tin selenide films described in this paper was based on two important properties of selenosulphate. One is its complexing ability, much like the well known complexing ability of thiosulphate a costly compound than selenosulphate. Tin selenosulphate complexes are formed in excess of selenosulphate. The other one is the ability of selenosulphate to gradually release selenide ions upon hydrolytic decomposition in alkaline media. The released selenide ions then combine with the tin ions released from the tin selenosulphate complexes upon hydrolysis and finally precipitating in to Nanocrystalline SnSe. In the fourth step these precipitates were filtered and deposited on to glass S ) ( 3 2 ) ( 3 2 ) ( aq aq S SeSo Na So Na Se   O H Se OH HSe 2 2       2 4 2 3        So HSe OH SeSo SnSe Se Sn     2 2