Study of structural and optical properties of chemically synthesized nanostructured cadmium zinc sulphide films for band gap tunability

Abstract

Nanostructured cadmium zinc sulphide films have been deposited onto cleaned glass substrates by chemical bath deposition method at room temperature using polyvinyl alcohol as capping agent. X-ray diffraction analysis confirms the formation of cubic-phase cadmium zinc sulphide films. Crystallite size obtained from the calculation of Scherrer's formula and Williamson-Hall plot as well as size-strain plot is found to decrease with the increase in zinc concentration. The films have very high dislocation density of the order of 10 16 m -2 , whereas the strain is of the order of 10 -3 . Scanning electron microscopic image reveals that the particles are agglomerated to form nanoclusters and energy-dispersive X-ray analysis confirms that films are composed of cadmium, zinc and sulphur. High-resolution transmission electron microscopic image reveals that the shape of the particles is nearly spherical, uniformly distributed. Selected-area electron diffraction pattern supports the formation of cubic phase of the film. Optical absorption peaks of the films shift towards lower wavelength side and their optical band gap increases with the increase in zinc concentration. The increase in zinc concentration enhances the photoluminescence emission intensity, whose emission is in the green region of visible spectrum.

X-Ray Analysis of Cadmium Oxide Nanostructured Films Synthesized with Different Precursor Molarities by Silar Method

“…Crystallite size, lattice strain and stress have been calculated using WilliamsonHall method, modified Williamson-Hall method and uniform deformation energy density model [15][16][17]. Size-strain plot (SSP) have also been used for finding size and strain of the prepared films [14,18,19], which is also used here. As far our best of knowledge modified Williamson-Hall method for structural characterization is used mainly for CdS, PbS, ZnO, etc.…”