, La 1ère Ecole d’Automne sur les Matériaux Emergents(EAME)

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Optical and morphological characterization of thin films obtained by electrochemical deposition
Ibrahim Yaacoub Bouderbala, Abdelmadjid Herbadji, Loubna Mentar

Dernière modification: 2017-11-18


Doping is a promising method of engineering the electronic structure of a metal oxide (thin film) to modify its optical and electrical properties. Using electrodeposition to elaborate Cu2O thin films is a well-established preparation method. It has been reported that chlorine doping is an effective process to change the morphology and reduce the resistivity of Cu2O thin films. Substitutional doping in Cu2O n-type can go into either Cu site or O sites. Based on the valence of Cu, +1, and O, −2, in cuprous oxide, the potential dopants n-type include group VII elements for oxygen sites and group II elements for copper sites. Our work focuses on halogens such as chlorine as n-type dopants in Cu2O. Out of all the halogens, F is best size-matched to O, but CuF is soluble in water. In this study, n-type doped Cu2O are deposited by electrochemical method, by introducing substitutional n-type dopant Cl on FTO. From baths with different precursor chlorine (CuCl2, NaCl and KCl), the change in the conductivity type from p type to n type was established and a systematic study was carried out to determine the influence of the nature of precursor onthe optical properties of Cu2O. The effects of Cl precursor were investigated by X-ray diffraction (XRD), photoluminescence (PL), UV-Vis-IR spectrophotometry, atomic force microscopy (AFM) and photocurrent. The measurements of X-rays diffraction (XRD) confirm that the films are pure Cu2O with polycrystalline structure and (111) phase which is strong out of plane texture for Cu2O films. The photocurrent measurements shows that the conduction type changes from p-type to n-type. The optical measurements show a direct band gap depending on the Cl precursor. AFM images reveal that the choice of the precursor doping has a very significant influence on the surface morphology and size of the crystallites of thin Cu2O