Electrochemical synthesis of thermoelectric SnTe compound

Thermoelectric materials are special types of semiconductors that can directly convert heat to electrical energy. SnTe is used in mid-IR photodectectors and thermoelectric heat converters.A few numbers of thin film preparing methods are used in the constructions of high quality thermoelectrical devices. In this study, co-deposition technique was applied to opd potentials, which can deposite species from same solution simultaneously.Tin telluride (SnTe) thin films were synthesized onto Au(111) substrates from an aqueous solution containing SnCl2, TeO2, and C6H5Na3 at room temperature (25oC) for the first time via electrochemical route. The overpotential deposition (opd) potentials of Sn and Te have been determined by the cyclic voltammetric studies. The films were grown from a system that obtained from mixing equal volumes of 25 mM SnCl2.2H2O,1 mM TeO2 , 27 mM C6H5Na3.2H2O electrolytes in 0,2 M HNO3 at a potential of -0,50 V vs Ag|AgCl (3 M NaCl).X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were applied to characterize the thin films. The as-deposited thin films were crystallized in the preferential orientation along the (220) plane. SEM investigations indicated that the shape of thin films could be altered from a spherical particle to a dendritic crystal by increasing the deposition potential. The optical absorption studies as a function of deposition time indicated that the band gap of the SnTe thin film increases as the deposition time decreases.