A Comprehensive Review on Chemical Bath Deposited ZnS Thin Film

Abstract

Chemical methods for synthesizing metal chalcogenides are currently receiving wide attention because of their simplicity, cost effectiveness and suitability for large scale deposition. Thin films can be deposited on variety of substrate such as insulators, semiconductor or metal because of lower temperature associated with these methods reduces chances of oxidation and corrosion of substrate. Slow release of anions in these processes facilitates better crystallinity with improved grain structure. Depending upon bath parameter, film deposition can take place by ion-ion mechanism of materials on the substrate or adsorption of hydroxide intermediate on substrate. Using these methods, thin films of group II-VI, III-VI, V-VI etc. have been deposited. Photo-sensor, photocells, detectors, photoluminescence, photovoltaic materials, thermo-electric materials, pigments, anti-reflective coating, optical memories, crude petroleum processing etc. are some of the application of metal chalcogenide films. In the present review article, we have described brief theoretical background necessary for chemical deposition. We discussed CBD method in details to obtain well-adherent and uniform thin film of ZnS. Their bath parameter, structural, morphological, optical, electrical properties etc. are also described.

The chemical process for materials deposition in aqueous solution: a review

“…The control of the main parameters during the chemical bath process is relatively easy and systematic. The most common reported materials are metal chalcogenides (sulphides and selenides) followed by tellurides [1,12]. Chalcogenides deposition by CBD consists in the slow precipitation of the basic material when the metal ions and chalcogenide ions react in alkaline aqueous solutions [13].…”

“…The b counter in Equations ( 12)-( 14) depends on the identity of the metal 12). This counter contemplates the sequential position (namely numbering) of the remainder reactions considering the last complexation reaction of zinc or cadmium with ammonia ligands.…”

“…, Equation (12), and in consequence, the complexation reactions for cadmium with hydroxyl ligands are numbered from (B.13) to (B.16) in the section B of the Supplementary Information.…”

“…Such species travel in a medium and then condensate at the substrate. A key concept here is the solubility product ( K sp ), a value which must be exceeded by the ionic product to initiate the formation of the species; otherwise, the solid phase will be dissolved back [4,12,32,33]. K sp mainly depends on bath temperature, type of solvent, and particle size [32].…”

The role of Zn-complexing agents in the chemical bath deposition of ZnO and ZnS thin films

“…Regarding to ZnS, its low solubility product (Ksp = 10 -24.7 , at room temperature) gave place to a fast homogeneous phase precipitation and precursor depletion; to study the role of complexing agent on deposition is very important because it controls the growth rate of solid species promoting the deposition of uniform and homogenous films [18]. The CBD deposition of ZnS films has been reported by Khatri and Patel, the results of several zinc and sulfur precursors are reported emphasizing the positive effect of sodium citrate and triethanolamine on the structural and optoelectronic properties of the films [19].…”