Preparation and characterisation of thickness dependent nano-structured ZnS thin films by sol–gel technique

Abstract

Zinc sulfide (ZnS) thin films of different thickness were coated on glass substrates by the sol-gel dip-coating technique. Thickness dependent structural and optical properties of the films were studied in detail. X-ray diffraction (XRD) analysis indicated that the films had mixture of cubic (b) and hexagonal (a) phases with cubic (b) phase being predominant. Scanning electron microscope (SEM) showed that the film surfaces were smooth and crack free. Energy dispersive X-ray (EDX) measurement showed no impurity in the ZnS compound with elemental concentration of Zn/S being 50.38/49.62. Optical measurements showed that optical transmittance of the films were decreased in the visible range as the film thickness increased and band gap of the thin films were estimated to be about 3.61, 3.56, and 3.39 eV for the films with thickness of 100, 220, and 360 nm, respectively. Reactive indices and extinction coefficients of the films were measured by Spectroscopic Ellipsometer. Both the refractive index (n) and extinction coefficient (k) of the films were increased as the film thickness decreased. Electrical measurements showed that the resistivity of the films were decreased as the substrate temperature and film thickness increased.

Nanostructured Cu-doped ZnS polycrystalline thin films produced by a wet chemical route: the influences of Cu doping and film thickness on the structural, optical and electrical properties

“…Among the II-IV class semiconductors, the ZnS characterized by a direct band gap of 3.7 eV and a large exciton banding energy (40 eV) has received huge interest [4][5][6][7][8][9][10] due to its chemical efficiency, non toxicity and therefore more environmentally friendly in comparison with other II-IV class semiconductors and other chalcogenides like ZnSe. Consequently, ZnS is considered to be a promising host material and semiconductor to be used as Cd-free buffer layers in polycrystalline thin film photovoltaic cells.…”

Effects of Al content on physical properties of ZnS thin films prepared by chemical bath deposition

“…It has potential applications in optoelectronic devices [1] such as IR windows, photocatalytic degradation, bio-medical imaging and dilute magnetic semiconductors as [2,3], their wide-band-gap of 3.7 eV [4] could decrease the window absorption losses and improve the short-circuit current of the cells. To fabricate high quality ZnS thin films, various growth techniques have been used such as sol-gel [5], radio frequency magnetron sputtering [6], molecular beam epitaxy [7], spray pyrolysis [8], chemical vapor deposition [9], reverse micelle method [10], wet chemical route [11], microwave heating technique [12], hydrothermal technique [13] and chemical bath deposition (CBD) [14].…”

Structural, morphological and optical properties of annealed ZnS thin films deposited by spray technique

“…ZnS has been widely used in optoelectronic device application including optical switching device, photo catalysts and optical sensors because of its outstanding properties such as the wide band gap (3.65 eV), and the high dielectric constant [1,2]. In the area of optics, ZnS can be used as a reflector and dielectric filter because of its high refractive index (2.35) and its high transmittance in the visible range, respectively [3,4]. Moreover, ZnS enjoys the advantages that it is perfectly lattice matched with Si substrate (0.2 %), which make it a promising material for the integration of optoelectronic devices onto Si substrates [5].…”