Growth Kinetics of ZnS Thin Films from a High-Rate Chemical Bath Deposition with Trisodium-Nitrilotriacetate Complexing

Abstract

In this study, a quartz crystal microbalance was used to perform in-situ study of ZnS growth using a chemical bath with Trisodiumnitrilotriacetate Complexing. In contrast to ex-situ studies, three deposition regions can be distinctly observed from the first twenty minute of growth curves based on in-situ measurements. The activation energy, as determined by the Arrhenius equation was found to be 66.22 kJ mol −1 and 36.32 kJ mol −1 for the first and second growth regions respectively. The growth curves suggest that ZnS film growth is initiated by an ion-by-ion reaction mechanism followed by a cluster-by-cluster deposition in the second growth region, and then is terminated by a terminal growth region where the deposition rate gradually slows down and eventually stops due to depletion of reactive species. An empirical rate equation describing ZnS thin film growth kinetics for the linear portion of the cluster-by-cluster growth region was obtained by fitting the growth rates as a function of the precursor concentrations. The improved understanding of growth mechanism and reaction kinetics could benefit future work toward designing more efficient chemical bath deposition process to fabricate nanocrystalline ZnS films for different applications.

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

“…ZnS thin film deposition has been carried out employing physical and chemical techniques, such as: sputtering [10], thermal evaporation [11], pulsed laser deposition [12], electrodeposition [13], Chemical bath deposition [14], and successive ionic layer adsorption and reaction (SILAR) [15]. Also, ZnS thin films have been prepared using a precursor solution by dip-coating [16] or spin-coating [17].…”