CdS Nanofilms: Synthesis and the role of annealing on structural and optical properties

Abstract

Cadmium sulfide (CdS) nanofilms have been deposited on the glass substrate using the chemical bath technique. Cadmium chloride and thiourea have been used as Cd2þ and S2 ion sources with ammonia as a complexing agent in the presence of a nonionic surfactant. The deposited films have been annealed in air at 373 K, 473K, 573 K, and 673K65K temperature. The effect of the annealing on the structure, morphology, and optical properties of CdS nanofilms has been studied. CdS films have been characterized by X-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, and UV-Vis-NIR spectrophotometer. The CdS films have been found to be nanocrystalline in nature with the zinc blende structure. The direct bandgap has been determined. Various parameters, viz. the grain size, inter-planer spacing, lattice constant, dislocation density, microstrain, surface morphology, absorption coefficient, and optical bandgap has been calculated and found to vary with annealing. The results have been explained on the basis of structural, surface, and optical changes.