Effect of chlorine doping on electrodeposited cuprous oxide thin films on Ti substrates

Abstract

Highly photoactive Cl-doped Cu2O films were electrodepos ited potentiostatically on Ti substrates. Optimum deposition potential was determined by Linear-Sweep Voltammetry measurements. The influence of chlorine doping on grain size, crystallite shape and orientation was examined using scanning electron microscopy and X-ray diffraction. X-ray photoelectron spectroscopy confirmed the presence of Cl due to doping. Mott–Schottky electrochemical impedance analysis showed the p-type conductivity for undoped Cu2O films and n type conductivity for Cl-doped Cu2O films. Analysis also showed that the carrier concentration of Cu2O thin films varied with Cl concentration of the deposition bath. Spectral responses of the resulting films were investigated in a photo-electrochemical cell to optimize the CuCl2 concen tration of the deposition bath to obtain highly photoactive films. Photocurrent measurements further confirmed that the conductivity of these Cl-doped Cu2O films was n-type while undoped films showed p-type conductivity at a bath pH 9.3. The resistivity of Cu2O films decreased with the Cl concentration and the resistivity obtained for the Cl-doped Cu2O films with the highest photoactivity was about 102 Vcm at 30 8C. The low resistance and high photoactivity of Cl doped cuprous oxide thin films make them more suitable for solar cell and other applications.