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Nanocrystalline CdS thin films have been prepared by the sol-gel spin-coating method. The influence of spin-coating process parameters such as, thiourea concentration (U), annealing temperature (A), rotational speed (S), and annealing time (T), and so on, on the properties of the prepared films have been studied. The experiments have been carried out based on four factor-five-level central composite designs with the full replication technique, and mathematical models have been developed using regression technique. The central composite rotatable design has been used to minimize the number of experimental parameters. The analysis of variance technique is applied to check the validity of the developed models. The developed mathematical model can be used effectively to predict the particle size in CdS nanocrystalline thin films at 95 pct confidence level. The results have been verified by depositing the films using the same condition. An ultraviolet-visible optical spectroscopy study was carried out to determine the band gap of the CdS nanocrystalline thin films. The band gap has been observed to depend strongly on particle size, and it indicated a blue shift caused by quantum confinement effects. The high-resolution transmission electron microscopy analysis showed the grain size of the prepared CdS film to be 6 nm. The main and interaction effects of deposition parameters on the properties of CdS nanocrystalline thin films also have been studied. [ABSTRACT FROM AUTHOR]

CdS quantum dots have been prepared by chemical method. The X-ray diffraction results indicated the formation of CdS nanoparticles with hexagonal phase and grain size 2.5 nm. The HRTEM analysis reveals the formation of CdS quantum dots with an average grain size of ~2.5 nm. The X-ray photoelectron spectroscopy spectra exhibit the 3 d5/2 and 3 d3/2 peaks corresponding to cadmium and the S2 p3/2 peak corresponding to sulphur. Optical studies by UV–vis spectroscopy show a blue shifted absorption at 471 nm because of the quantum confined excitonic absorption. The photoluminescence spectra of CdS exhibited a broad green emission band centred at around 494 nm. [ABSTRACT FROM AUTHOR]

CdS nanocrystalline thin films have been prepared by sol-gel spin coating method. CdS nanoparticle thin films have been prepared using cadmium nitrate as cadmium source and thiourea as sulfur source. The effect of annealing on the properties of the prepared CdS nanocrystalline films has been studied. The x-ray diffraction studies indicated the formation of nanocrystalline CdS thin films with hexagonal phase. The grain size has been found to lie in the range of 5 to 8.2 nm depending on the annealing temperature suggesting the formation of CdS quantum dots. These results have been confirmed using high resolution transmission electron microscope (HRTEM) analysis which also indicated the formation of nanocrystalline CdS with a grain size of nearly 5 nm. The absorption spectra demonstrated the presence of quantum confinement effect in the prepared CdS nanocrystalline films because of the small size of the particles. The photoluminescence spectra of the CdS films exhibited green and yellow emission bands. [ABSTRACT FROM AUTHOR]