Studies of electrosynthesized zinc selenide thin films

Zinc selenide (ZnSe) is an important opto-electronic semiconducting material with a wide band gap of 2.7 eV at room temperature. Even though many techniques are used for the preparation of ZnSe thin films, electrochemical deposition from aqueous solution attracts much attention in recent years, due to its low cost and ability to control the film properties by varying the deposition parameters. The structural and optical properties of ZnSe layers are deeply influenced by the bath parameters in the electrochemical deposition. In the present work, the electrochemical deposition and characterization of zinc selenide thin films are reported. ZnSe thin films were deposited onto tin oxide coated conducting glass substrates from an aqueous solution bath containing ZnSO₄ and SeO₂. Cyclic voltammetric study was used to optimize the deposition potential range for the co-deposition of zinc and selenium. The optimum deposition conditions to obtain stoichiometric ZnSe thin films were found as: Deposition potential: -0.8 to -1.0 V versus SCE, solutionpH: 3.5±0.1, Bath temperature: 80°C. X-ray diffraction studies reveal cubic ZnSe with a preferred orientation along (111) plane. Raman spectroscopic studies reveal optical phonon peak corresponding to crystalline ZnSe. The effects of deposition parameters such as bath temperature, electrolyte concentration and deposition potential on the properties of ZnSe thin films are studied and the results are discussed.