Caractérisation structurale et optique de couches minces formées par des agrégats des nanocristaux de ZnO.

Abstract

This thesis concerns the development and characterization of thin films of ZnO, which were conducted at temperatures close to room temperature using the Sol- Gel photo assisted method with a deposition technique “Dip Coating.” The samples were prepared according to the protocol following: mixing the precursor of zinc acetate dehydrate and the solvent 2-methoxyethanol with monoethanolamine as a stabilizer. Structural characterization of thin films of ZnO was carried out by X-ray diffraction. It confirmed first, the formation of crystallites of ZnO for samples irradiated by UV light and secondly to determine their crystal structures and their small size does not exceed a few of nanometers. Characterization by measurement of optical absorption in the UV-visible area, showed a shift of absorption edge for ZnO layers to high energies (short wavelengths) compared to that of bulk crystal of the latter .This discrepancy is due to quantum confinement effect induced by size reduction. A second optical characterization by photo luminescence measurement showed that the samples prepared exhibit intense emission bands in the visible and near UV. This observation led us to practical applications in area of optics and photovoltaics.