Available online at www.scholarsresearchlibrary.com Scholars Research Library Archives of Physics Research, 2012, 3 (5):367-377 (http://scholarsresearchlibrary.com/archive.html) ISSN : 0976-0970 CODEN (USA): APRRC7 367 Scholars Research Library Influence of acetic acid complex on physical properties of spray deposited FeSe thin films A. U. Ubale * , Y. S. Sakhare Nanostructured Thin Film Materials Laboratory, Department of Physics,Govt. Vidarbha Institute of Science and Humanities, Amravati, India _____________________________________________________________________________________________ ABSTRACT The iron selenide thin films were successfully deposited on to the glass substrates at 573 K temperature using spray pyrolysis technique. Along with Fe and Se source, acetic acid (CH 3 -COOH) was used as a complexing agent during the deposition process. The structural, morphological, electrical and optical properties of the deposited films have been studied using X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-Vis spectrophotometer respectively. The XRD analysis shows that the spray deposited FeSe thin films are nano- crystalline with tetragonal lattice. The surface studies of FeSe films shows porous morphology with spherical grains which is improved with addition of acetic acid. The AFM image indicates that the as deposited FeSe thin films are uniform, compact and well covered to the substrate. The absorption studies shows that films have direct band gap which varies between 3.05 to 2.60 eV depending on the quality of acetic acid added in the spray solution. The variation of electrical resistivity with temperature confirms semiconductor behavior of FeSe. Keywords: Chalcogenides, Spray pyrolysis, SEM, AFM, Electrical and Optical properties. _____________________________________________________________________________________________ INTRODUCTION The nanocrystalline materials have opened an innovative phase in the field of electronic applications, since material properties could be changed by changing the crystallite size and/or thickness of the film. The transition metal chalcogenides represent an significant family of materials useful in various devices such as solar cells [1–6] superconductors [7, 8], sensors [9] and various in spintronicsdevices [10–12]. Iron selenide is an important compound from this group which is usually prepared by several techniques viz. sulphuration of iron predeposited films [13], selenization of evaporated iron thin films [14],low-pressure metal organic chemical vapor deposition (LP-MOCVD) [15], mechano-synthesis [16], selenization technique [17], molecular beam epitaxy [18], milling pure elemental powder of iron and selenium [19] and selenization of amorphous iron oxide thin films prepared by spray pyrolysis [20, 21]. Chen at al [22] have prepared FeSe thin films with tetragonal structure by electrochemical deposition method. The deposition mechanism was inferred that the Se 4+ ions are reduced to Se and successively oxidized to Se 2- , which forms tetragonal FeSe with Fe 2+ . Chen et al [23] have reported growth of epitaxial tetragonal iron selenide thin films on single crystal SrTiO 3 (001) and MgO (001) substrates by pulsed laser deposition method. The deposition temperature and annealing temperature are found critical for getting tetragonal phase of FeSe .The synthesis of nanocrystalline metal chalcogenide thin films by spray pyrolysis techniques is currently attracting considerable attention as it is comparatively inexpensive, simple and convenient for large area deposition. The aim of the present work is to develop spray pyrolysis method for the preparation of nanocrystalline FeSe thin films. The