Effect of Zn Doping in CdS Thin Films on Structural, Morphological and Optical Characterization

Abstract

In this particular experiment we employ Chemical Bath deposition Technique. Initially the bath parameters such as temperature, pH of the precursors, molarity of the solutions, deposition time were optimized for synthesis of CdS thin films. Using above optimized parameters, we prepare Cd1-xZnxS thin films for the study of effect of Zn concentration on various properties of the films. The structural, Morphological and optical characterization were investigated. The XRD spectra of the Cd1-xZnxS films exhibit the hexagonal crystal structure with preferential orientations at (100), (002), (101), (203), (102), (110), (200) and (004) planes. The planes (101), (002), (100) exhibited the wurtzite (hexagonal type) structure. XRD pattern shows increase in half width at full maximum with Zn content. SEM micrograph shows the porous fibrous network consisting of regularly arranged matrix over which regular shaped fine particles systematically distributed. The effect of Zn concentration in Cd1-xZnxS thin films clearly understood from the improvement in the microstructure of the surface morphology. The optical spectra show that absorption was found decreased with Zn content of the Cd1xZnxS.The absorption spectra shows the significant blue shifting of absorption edge (approximately from 450 – 325 nm). The optical transmittance was found maximum in the visible region (450 800 nm) and increased on increasing the Zn concentration. The x=0.2 composition having maximum transmittance 78% show the maximum 3.9 eV optical band gap which may be high enough for solar cell applications.