SYNTHESIS, STRUCTURAL AND OPTICAL CHARACTERIZATION OF PVA CAPPED CADMIUM SULPHIDE NANOCRYSTALLINE FILMS BY CHEMICAL BATH DEPOSITION METHOD

摘要

Nanocrystalline CdS thin films were deposited on glass substrate by chemical bath deposition method using Cadmium Sulphate and Thiourea as Cd~(+2) and S~(-2) ion sources for different molarities i.e. 0.1 M, 0.2 M and 0.3 M. The crystallite size and lattice parameters for each sample were determined from X-Ray diffraction data using Scherrer's formula. The value of the crystallite size was found to be within the range 14.7 nm-11.4 nm. The optical characterization was done by UV-Visible and photoluminescence spectroscopy. The optical band gap of the films was determined from the transmittance spectra. It was observed that when the molarity increases, the average crystallite size decreases and the band gap energy of the prepared films increases. Photoluminescence studies showed a prominent peak at around 530 nm. The radius of the nanocrystalline films had been evaluated from the absorption spectrum by using effective mass approximation formula.