Electrochemical determination of CdS band edges and semiconducting parameters

Cadmium sulfide (CdS) thin film was electrodeposited on indium tin oxide (ITO) by chronoamperometry. The SEM images showed that hexagonal sheets of CdS deposited on the ITO surface. The X-ray diffraction (XRD) analysis confirmed this structure for CdS crystals and the average of crystalline size and the lattice constant parameters are approximately 39.54 and a = 0.4136, c = 0.6696 nm respectively. Photo-electrochemical investigations were performed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques. CdS band edges and density of states (DOS) were determined by CV technique. The band gap energy (E_bg) was measured by ultraviolet–visible (UV–vis) spectroscopy and electrochemical methods. Mott–Schottky plots were used to find the values of flat band potential (E_fb), donor density (N_D) and Debye length (L_D). Also, the position of surface states was investigated by Mott–Schottky and LSV techniques. EIS was employed to confirm our electrochemical findings and investigate the charge transfer mechanism. (author)