Structural and optical studies on La doped CdS nanocrystalline films

This paper reports the synthesis of pure and lanthanum (La) doped nanocrystalline CdS semiconducting films on the glass substrate by means of chemical bath deposition (CBD), with Cd(CH3 COO)2 as Cadmium (Cd) ion source, (NH2)2CS as sulphur (S) ion source and Thioglycerol as capping agent. Long, rod like structures is observed in SEM micrographs of the films. XRD studies show the existence of both hexagonal and cubic phases. Increase in FWHM is observed for smaller particle due to nanocrystalline effect. UV-VIS absorption studies show shift of absorption edge towards lower wavelength side. Corresponding change in band gap energy results in shift of photoluminescence edge emission spectra. Also emission peaks near 366 nm are observed under 230 nm excitation due to transitions at higher energy levels.