Elaboration et caractérisation des couches minces nanocristallines

Abstract

"Thin films zinc oxide nanocristallins (ZnO) and films nanocomposites of tin oxide dispersed in polystyrene (Ps/SnO2) were elaborate at ambient temperature by the sol gel method by using the techniques of dip-coating and spin-coating respectively. In order, the chemicals products used in the first case were the zinc acetate, the ethanol and diethanolamine as a starting powder, solvent and a catalyst. On the other hand in the case second, polystyrene, the chloroform and the powder of tin oxide constituted the starting matrix, solvent and the doping agent. The diffraction of x-rays (DRX), the spectroscopy of x-ray fluorescence and the vibrationnelle spectroscopy were used in the structural characterization. The indexing of the peaks of the DRX show that the thin films of ZnO have a hexagonal structure (standard wurtzite) whereas that of SnO2 in the Ps/SnO2 films have a tétragonale structure (standard rutile).the deduction of the sizes of crystallites confirms the order nanometric of elaborate films. Moreover, the attribution of the modes of the molecular vibrations, obtained by the vibrationnelles spectroscopies infra-red (FTIR) and Raman, confirms the presence of the molecules of ZnO and SnO2. The optical characterization by the U.V-visible spectroscopy, shows the transparency of thin films of ZnO in the visible one and the infra-red close (400cm -1 - 800cm -1) with a gap Eg = 3.39 eV and an index of refraction n = 2.76. In films of Ps/SnO2 the gap Eg = 3.35 eV and an index of refraction n = 2.18 In end, by the method of the four points, the resistivity of thin films was estimated."