Chemical Bath Deposition, or Chemical Solution Deposition, (also known by the acronyms CBD and CSD) is a chemical process through which a thin film of material is deposited. Typically, a liquid solution containing precursors to the eventual film is prepared and a substrate is exposed the solution. Over the course of seconds or minutes (depending on the reagents and their concentrations), the precursors react to produce a solid material that grows, atom by atom, on all the surfaces exposed to the bath.
This method of deposition, compared to other thin film deposition methods, is often noted for its low cost and for the simple apparatus required to perform the deposition. It is, however, not always an option for thin film growth, as a suitable precursor solution does not exist for every material.
Uses
editChemical bath deposition is regularly used in the photovoltaic industry to deposit thin films of cadmium sulfide. For this deposition, the chemical bath is prepared by mixing a cadmium precursor (i.e. cadmium chloride, or cadmium sulfate) with a sulfide precursor (i.e. thiourea) in alkaline water. The cadmium precursor reacts with the sulfide precursor in such a way that the surfaces exposed to the bath become coated with a thin film of cadmium sulfide (typically 25-500 nm thick).
This process has also been used to apply thin films of silver to glass for the purpose of producing a mirror. While most mirrors are no longer made this way, this reaction is occasionally performed in chemistry classes to produce mirrored glassware.