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Structural and optoelectronic properties of copper, zinc, cadmium and lead chalcogenide nanocrystalline thin films deposited at the water-toluene interface
(2013-08-12) Asare-Donkor, Noah Kyame
Nanostructured thin films of CuE (E=S, Se, Te) have been prepared at the water-toluene interface by reacting toluene solutions of copper cupferronates with aqueous chalcogenide ions obtained by the borohydride reduction of sulphur, selenium and tellurium powder. The thin film deposits were characterized by powder X-ray crystallography, scanning electron microscopy and absorption spectroscopy. The influence of deposition conditions such as precursor concentrations, temperature as well as deposition times were studied. The average crystallite sizes of the as-prepared nanoparticles at different temperatures, concentrations and deposition times ranged from 3.4 to 4.3 nm for CuS, 5.1 to 5.7 nm for CuSe and 1.4 to 4.5 nm for CuTe. The dislocation densities ranged from 5.46 to 8.85 x 1017 lines/m for CuS and 2.32 to 3.86 x 1017 lines/m for CuSe, 5.0 to 47.91 x 1017 lines/m for CuTe. The shape of the as-prepared nanoparticles at different temperatures was studied by SEM and gave morphologies from cubes to rods. The band gaps obtained for CuS ranged from 3.6 to 3.9 eV and CuSe ranged from 3.53 to 3.96 eV