ABSTRACT
Hexagonal cadmium sulfide (CdS) thin films were deposited on glass substrates by Aerosol Assisted Chemical Vapour Deposition (AACVD) using cadmium(II) dithiocarbamate and xanthate complexes in tetrahydrofuran (THF) and mixed solvents (THF+ chloroform) at 400 and 450 oC. The surface morphology and size of the CdS films determined using scanning electron microscopy (SEM), showed the formation of films of various morphologies depending on the precursor, the deposition temperature and solvent used. An increase in temperature resulted in an increase in particle size and a change in morphology with the formation of CdS films with distorted structures. The CdS films showed an overall blue shift in their absorption band edge (2.35 – 2.49 eV) compared to the bulk CdS. In dithiocarbamates, a slight blue shift was observed with a shift to high wavelengths with the reduction of the carbon chain of the dithiocarbamate and an increase in temperature; while in xanthate, a strong blue shift was observed at both deposition temperatures. The use of mixed THF + chloroform solvent at 450 oC showed the formation of films with irregular structures compared to those deposited using THF solvent alone, indicating the role of the solvent in the shape direction of the films formation. The elemental composition determined by energy dispersive X-ray spectroscopy (EDX) measurements revealed the 1:1 (Cd:S) ratio in all the samples confirming the stoichiometry of the CdS films.
Royal Society—Department For International Development (RS–DFID) capacity building initiative and the National Research Foundation (NRF) South Africa through the South African Research Chair Initiative (SARChi)