GROWTH AND CHARACTERIZATION OF NANOCRYSTALLINE CdS THIN FILMS

摘要

Nanocrystalline cadmium sulfide (CdS) thin films were deposited by thermal vacuum evaporation (TVE) from single source onto ITO covered optical glass substrates. These films were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM) and spectroscopic ellipsometry (SE) in the range of 250 – 1700 nm. The optical constants as well as the films thicknesses and the optical band gaps were obtained by fitting the experimental psi and del spectra from ellipsometric measurements. The recorded data were analyzed using a dedicated software package specially designed for optical modeling. The ellipsometrical parameters psi and del were acquired at three incidence angles (65°, 70°, 75°) for a high number of wavelenghts in the mentioned wavelength range.In order to determine the refractive index, the thickness and the surface roughness of CdS thin films, as well as for obtaining a smooth control for the experimental data fitting processes, the identification of the spectral regions in which the films showed good transparency is required. This working procedure generates a significantly increased number of optical models with a slightly reduced number of fitting parameters