MORPHOLOGICAL, STRUCTURAL AND OPTICAL CHARACTERIZATIONS OF Zn-DOPED CdS BUFFER LAYER ELABORATED BY CHEMICAL BATH DEPOSITION

Abstract

Zn-doped CdS layers, with various percentage ratios [Formula: see text] (= [Zn[Formula: see text]]/[Cd[Formula: see text]]%) were grown on glass substrates by chemical bath deposition (CBD). The effect of Zn-doping on different properties of CdS is studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, atomic force microscopy, energy dispersive X-ray analysis and UV-visible diffuse reflectance. The XRD patterns indicated polycrystalline films with (111) orientation and the insertion of Zn does not change the crystallinity of CdS. The Raman spectra show one major peak centered around 300[Formula: see text]cm[Formula: see text] assigned to the first-order longitudinal optic (LO) phonon modes of CdS. The surface morphology visualized by AFM and SEM analysis showed the influence of the Zn-doping on the morphology of the films, the surface roughness is found to decrease from 16.5 to 8.9[Formula: see text]nm with augmenting the ratio [Formula: see text] from 0 to 6%. In regard to the SEM analysis, the increase of [Formula: see text] yielded a lower porosity of the film and voids, and the films become more homogeneous. The EDAX spectra confirmed the existence of Zn in the doped samples. The bandgap decreases from 2.44 to 2.37[Formula: see text]eV, while the transmittance increases from 76 to 86% with augmenting the ratio [Formula: see text].