Structural and Optoelectronic Properties of Zinc Sulfide Thin Films Synthesized by Co-Precipitation Method

Abstract

Wide bandgap Zinc Sulfide nanocrystals are prepared by a simple co-precipitation method at different precursor concentrations. The influence of sulphur concentration in Zinc sulfide on morphological, optical and electric properties is found to be significant. The Zinc Sulfide nanomaterial was prepared using low-cost starting materials and deionised water as the solvent. As synthesized Zinc Sulfide nanocrystals were analyzed using X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS) analysis, UV-Visible Spectrophotometry, Photoluminescence (PL), Scanning electron Microscopy (SEM), Ellipsometry techniques and electric conductivity measurements. XRD patterns revealed that ZnS nanocrystals are polycrystalline, cubic phase with (111) preferred orientation. The obtained crystallites have sizes in the range of 5 to 11 nm. EDS pattern confirms the purity of the films. From optical absorption measurements, it is clear that the direct energy gap decreases from 5.2 to 4.4eV with the increase in sulphur concentration in ZnS and exhibit large quantum confinement effect. Ellipsometry was used to determine the optical constants and film thickness. The films deposited on ITO – coated glass was used to record the IV Characteristics of the films by two probe method. The wide-bandgap, conducting materials have applications in optoelectronic devices such as high-frequency UV detectors and thin-film solar cells.

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