Elaboration et Caractérisation des Couches minces du Semiconducteur ZnO pures et dopées par le Cadmium

Abstract

The present work consists in the elaboration and characterization of the undoped and cadmium-doped ZnO with different concentrations of cadmium (Cd) (1, 2, 5 and 10% in weight) thin films in order to improve the structural and optical properties of ZnO. The samples were prepared using two methods; Colloidal and Sol-Gel and deposited on glass and silicon substrates by the Dip-coating technique. The structural characterization showed the formation of ZnO with hexagonal structure (wurtzite) with a preferential orientation according to plane (002) (sol-gel method). With the exception of doping with 10% Cd (colloidal method), the formation of the ZnO/CdO nanocomposite was assisted. SEM and AFM images revealed the nanometric character of our films. The Raman diffusion confirmed the results of the DRX that is the formation of ZnO with hexagonal structure (wurtzite). The RBS spectroscopy has proved the existence, in our films, of the elements (zinc, cadmium and oxygen) and gave us an idea on the thickness of the thin films. The measurement of ellipsometry allowed us to evaluate the refractive index of our films and to estimate their thickness. UV-visible spectroscopy has shown that our layers have a transparency, in the visible, which varies between 70 and 90%. And that the gap decreases with the increase in doping. The photoluminescence of the films showed ultraviolet (UV) and visible emissions related to defects. Auger analysis on layers deposited on silicon substrates gave us an estimate of the thickness.