Electroplating Kinetic of Nanostructured Selenium Films from Citrate Bath

Abstract

In this work; Cyclic-Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were used to study the electrodeposition kinetic of selenium films in potentiostatic mode from aqueous solution containing selenium dioxide and sodium citrate at pH = 4.2. Semiconducting proprieties of obtained deposits were investigated by Mott-Schottky measurements whereas the optical ones were performed by UV–Visible spectrophotometry. The morphological characterization was carried out using the scanning electron microscopy (SEM). The obtained results showed that the electrodeposition process of selenium films in citrate bath occurred under diffusional regime as rate-limiting step. Deposition rate of selenium layers on platinum substrate is much superior than in the case of ITO substrate and up to a value of 0.65 μg/cm2 s. The HSeO3−/Se system becomes more rapid with the increase of the bath temperature. Obtained deposits are photoactive films that belong to p-type semiconductors with number of charge carriers in order of 1021/cm3 and energy band gap about 1.7 eV. The grains of electroplated films have spherical forms, nanometric sizes and strong adhesion on the substrate surface.