Structural and Spectroscopic Studies of Chalcogenide Nano Particles

CdSe Nano particles were grown by Chemical Bath Deposition. The pH of the solution was maintained at 11. The precipitate so obtained was annealed in air for about 4 hours at 3000C temperature. The annealed powdered samples were subjected to optical and structural characterization using UV-Visual spectrophotometer, Raman and XRD. Powdered XRD was used for structural characterization whereas UV-Visual and Raman spectroscopy were used for optical characterization. XRD spectra reveals that the grown CdSe nano particles are polycrystalline in nature and have hexagonal structure. The average particle size, using Debye-Scherer formula, in CdSe powdered sample was found to be of the order of 4.5nm. UV-Visual transmittance spectra recorded over the wavelength range 350 to 900 nm and Tau plots were used to calculate the band gap of CdSe Nano particles. It was found that the band gap is 1.7eV. Raman spectra of annealed CdSe powder shows that polycrystalline nature of the sample in nanocrystalline regime. Reported result shows that the Raman shift should decrease with an increase in nanocrystallite size.