Journal of Alloys and Compounds 488 (2009) 157–162 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Room temperature electrosynthesis of ZnSe thin films Y.G. Gudage, N.G. Deshpande, Abhay A. Sagade, Ramphal Sharma ∗ Thin film and Nanotechnology Laboratory, Department of Physics, Dr. B.A.M. University, Aurangabad 431004 (M.S.), India article info Article history: Received 13 July 2008 Received in revised form 1 November 2008 Accepted 5 November 2008 Available online 17 November 2008 Keywords: Electrosynthesis ZnSe X-ray diffraction Cubic phase Atomic force microscopy abstract In the present study, we report the room temperature electrosynthesis of Zinc selenide (ZnSe) thin films on stainless steel (SS) and fluorine doped tin oxide (FTO) coated glass substrates. In addition, the influence of the substrate on the microstructural properties of ZnSe is plausibly explained. Voltammetric curves were recorded in order to characterize the electrochemical behaviour of Zn 2+ /SeO 2 system. The as-deposited ZnSe thin films have been characterized for structural (X-ray diffraction (XRD)), surface morphological (scanning electron microscopy (SEM)), compositional (energy dispersive analysis by X-rays (EDAX)), sur- face topographical (atomic force microscopy (AFM)) and optical absorption analysis. Formation of cubic structure with preferential orientation along the (1 1 1) plane was confirmed from structural analysis. A significant observation seen from the SEM micrograph was the formation of porous layer on the FTO coated glass substrate. However, this is not seen in case of stainless steel substrate. Similar observation was predicted in case of AFM analysis for the films deposited on FTO. The optical band gap for ZnSe thin films was found to be 2.7 eV. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Synthesis and characterization of wide gap II–VI semiconduc- tors are of great importance, since these materials can be utilized in a variety of optoelectronic applications, viz. solar cells, hetero- junction LED, photoconductors, etc. Though Zinc selenide (ZnSe) has a direct wide band gap (2.7eV) it is exceptionally interesting material for the applications like optoelectronics, especially for fab- rication of the blue light diodes, also it acts as a buffer/window layer in chalcogenide-based thin film solar cells (by constructing a heterojunction under lattice matching conditions) [1–3]. There are several reports available on the growth of ZnSe thin films by various techniques such as chemical vapour deposition (CVD) [1], screen printing [4], vacuum evaporation [5,6], pulsed laser deposition (PLD) [7], chemical bath deposition (CBD) [8,9], etc. It has been identified that the deposition from aqueous solution makes the process simple, economical and easily scalable. CBD and electrochemical deposition (ECD) are the commonly known pop- ular techniques for the deposition of films from aqueous solution. Several authors have reported on the chemical bath deposition of ZnSe thin films from aqueous solution [9–11]. But, in CBD, the mate- rial wastage is high and the control over rate of deposition is rather difficult. Electrodeposition is one of the most widely accepted tech- ∗ Corresponding author at: Inorganic-Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791, South Korea. Tel.: +82 2 22925212; fax: +82 2 22200762. E-mail address: rps.phy@gmail.com (R. Sharma). niques for the economical and efficient growth of the films from aqueous solution, and numerous reports are available on the depo- sition of various thin films by this technique. But it is very surprising to note that the electrodeposition of ZnSe thin films has not been studied in comparison with cadmium chalcogenides. Also it is worth to note that electrodeposition of the ZnSe is difficult because of the wide difference in the reduction potential of Zn and Se ions [12], and only few reports are available on the electrodeposition of ZnSe thin films [12–17]. Abundant literature is available on preparation and character- ization of ZnSe by using ZnSO 4 and ZnCl 2 as source materials for “Zn 2+ ′′ source [12–18]. Selenious acid has been reported as a “Se 2- ′′ source by many workers [15,19]. However, no attempt is made on electrosynthesis of the ZnSe by using zinc acetate as a source of Zn 2+ from aqueous acidic bath. In view of this, an attempt has been made to electrosynthesize ZnSe thin films at different pH of the bath ranging from 2 to 3 at the interval of 0.5. The as-deposited films were studied for structural, surface morphological and opti- cal properties. In addition, the influence of the substrate on the microstructural properties have been studied and compared with the reported literature wherever necessary. 2. Experimental 2.1. Preparation of ZnSe thin films ZnSe thin films were electrodeposited potentiostatically by a conventional three- electrode set-up. Cyclic voltammetric measurements and the ZnSe electrodeposition were made by using a potentiostat (Princeton PerkinElmer, Applied Research Versa stat II; Model 250/270) in the three-electrode configuration. The cell consists of stainless steel (SS) and/or fluorine doped tin oxide (FTO) coated glass as the working 0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.11.036