Many galvanic coating processes (electrodeposition) rely on so-called additives that are added to the electrochemical bath. The enormous variety of different additives covers small amounts of certain atoms, organic molecules, and even larger chemical complexes, e.g. chlorine ions, benzotriazole,... These additives are essential, as they influence the precise structure and, therefore, also the quality of a coating. Moreover, certain plating processes are impossible without the support of particular additives. Although the plating industry strongly relies on the function of these additives, the underlying atomic scale processes are unknown in most cases. Consequently process optimization and electrolyte development are restricted to trial-and-error research.
We focus on a solution to this empirical approach by studying the function of the additive with
atomic resolution during the plating using video-rate, in-situ STM.
For this purpose, we have developed a very unique, electrochemical STM (EC-STM):
This microscope is not only capable of imaging with full video-rate (see also movies), but it also can quickly react to significant height changes that naturally occur during the electrodeposition/growth process. Moreover, we have developed a flow cell with special pumps such that we can exchange the electrolyte composition, and thereby the additives, while we measure with atomic resolution. Changes in the growth process become easily recognizable in this way. Finally we recently have even extended the flow cell with a connection to an external standard hydrogen electrode (SHE) such that we have full control and absolute potentials in our flow cell independently of the used electrolyte.
We have collaborations with the semiconducting industry to understand the superfilling process that is necessary to produce the newest generation computer chips.

Publications (click the link):
3) Structural Accelerating Effect of Chloride on Copper Electrodeposition
2) A general model of metal underpotential deposition in the presence of thiol-based additives based on an in situ STM study
1) Design of a high-speed electrochemical scanning tunneling microscope