Elaboration et caractérisation des couches minces du semi-conducteur ZnO non dopé et dopé par l’Argent.

Abstract

The present work consists in the elaboration and characterization of the undoped and silverdoped ZnO thin films with different concentrations of silver (Ag) (1,3,5,7 and 10% in weight) in order to improve the structural, morphological, optical, electrical and photocatalytic properties of ZnO. The samples were prepared using the Sol-Gel method and deposited on glass substrates by the Dip-coating ""Dipping-Drawing"" technique. The structural characterization showed the formation of ZnO of hexagonal structure (wurtzite) with a preferential orientation according to the plan (002) and allowedto determine the nanometric size of the crystallites. Only for doping with 10% Ag we observe the formation of the secondary phase AgO. SEM and AFM images revealed the nanometric character of our layers. Raman scattering confirmed the results of the XRD, namely the formation of ZnO with an hexagonal structure (wurtzite). UV-visible spectroscopy has shown that our layers have a transparency, in the visible range, which varies between 70 and 90%. And that the gap decreases with the increase in doping level. The photoluminescence of the films showed ultraviolet (UV) and visible emissions related to defects. Finally, we tested the photocatalytic efficiency of the undoped and silver-doped ZnO under UV irradiation regarding Methylene Blue dye degradation, It is noted that doping with silver improves the photocatalytic activity of thin films and that the highest activity is observed for ZnO doped with 7% of Ag