Characterization of enhanced optical and structural properties of CBD-CdS thin films by gold ions doping

In this work, the characterization of the enhanced structural and optical properties of the cadmium sulphide (CdS) nanostructured semiconductor associated with doping with metallic gold ions is presented. Thin films of good structural quality were obtained by chemical bath deposition and doped in-synthesis without the need for additional steps required. A controlled thickness of the thin films around 100 nm was confirmed by ellipsometry measurements. The binding energies of the CdS matrix and its interactions with the metallic gold ion were determined by X-ray photoelectron spectroscopy. The crystallinity and crystalline phase of the CdS matrix were studied by X-ray diffraction, obtaining that the predominant crystalline phase was Zinc blende. Furthermore, a change from monocrystalline to polycrystalline structure was observed in the gold-doped films, this behaviour was confirmed by TEM micrographs. In addition to the different levels of quantum confinement promoted by the transition metal. By Raman spectroscopy was confirmed that the predominant crystalline phase is zinc blende, additionally the vibrational Raman spectra allowed the analysis of the phononic interactions of the CdS binary where the Raman shift gives structural information and confirms the effects of quantum confinement. Optical properties were characterized by UV–Vis spectroscopy, which describes the effect of crystalline structural changes with shifts in the optical band gap energy of the evaluated samples with respect to the bulk CdS, related to the different levels of quantum confinement given by dopant metallic gold.