Dopage électrochimique des oxydes métalliques : applications aux photovoltaïque

Abstract

Doped and undoped ZnO nanostructures with different concentrations of Al were prepared by electrochemical deposition. The nanostructures were electrodeposited by cathodic polarization on a fluorine doped tin oxide substrate (FTO). From the cyclic voltammetry study, the kinetics of electrodeposited ZnO showed that introducing Al3+ ions into the electrolyte accelerates the reaction of the formation of the nanostructures. The study by chronoamperometry identified the mechanisms of the electrodeposition and the preparation of the films. The Schottky-Mott measures showed that the films have an n-type conductivity with an increase in the carrier concentration when the Al doping increase. The morphological characterization of the samples by atomic force microscopy (AFM) and scanning electron (SEM) showed a significant change of the topography with an increase in roughness during doping. X-ray diffraction (XRD) showed that all the samples are hexagonal Wurtzite structures and a preferred orientation along the c-axis. Also, the Al doping deteriorates the films crystallinity. The optical properties indicate that the transmission of all the samples is high and the optical band gap increases after doping from 3.22 to 3.47 eV. The PL spectra were used to determine the emission properties of the films. Electrical measurements showed that the doping of ZnO improves the electrical conductivity of the films.