Optical properties of CdS thin films

The properties of CdS thin films were investigated by applying atomic force microscopy (AFM), Raman and far-infrared spectroscopy. CdS thin films were prepared by using the thermal evaporation technique under base pressure 2 × 10−5 torr. The quality of these films was investigated by AFM spectroscopy. We applied Raman scattering and far-infrared spectroscopy to investigate the optical properties of CdS thin films, and reveal the existence of Surface Optical Phonon (SOP) mode at 297 cm−1. Effective permittivity of mixture was modeled by Maxwell–Garnet approximation. In the analysis of the far-infrared reflection spectra, a numerical model for calculating the reflectivity coefficient for a system which includes films and substrate was applied.

► CdS thin films were prepared using thermal evaporation technique.
► The morphology of films was investigated by atomic force microscopy (AFM).
► Optical properties were investigated applying Raman and far-infrared spectroscopy.
► Numerical model for the reflectivity coefficient which includes films and substrate.
► Existence of surface optical phonon modes.