Project B4 of SFB TR 87

Plasma diagnostics of pulsed microwave plasmas with HF-bias combined with plasma-enhanced atomic layer deposition for the deposition of multilayer SiOx gradient coatings as barrier coating of flexible polymers

In the frame of this project, fundamental mechanisms during the deposition of different types of coatings on polymers are analysed. Coatings are deposited by means of plasma enhanced chemical vapour deposition (PE-CVD) using a pulsed microwave plasma with additional HF-bias. Analysis includes the determination of absolute plasma parameters as well as thin film analysis of the resulting coatings with regards to chemical composition and morphology.
The second area of this project (lead by Prof. Anjana Devi, group Inorganic Materials Chemistry) deals with plasma-enhanced atomic layer deposition (PE-ALD).

The process of deposition can be summarised as follows: A silicon containing precursor, which provides the species necessary for the resulting coating, is fed into the process chamber and fragmented by the microwave plasma. By the addition of reactive gases such as oxygen, the fragmented precursor molecules will undergo chemical reactions thereby modifying the fragments e.g., by accumulating silicon-oxygen bonds. These fragments then deposit onto the polymer substrate where further surface reactions such as oxidation can take place.

The project investigates two types of coatings: Gas barrier coatings and gas separation membranes. While gas barriers are meant to prevent any type of gas (here specifically oxygen and water vapour) to permeate through the material, gas separation membranes are designed to allow permeation only for a specific gas type.
In an industrial context, these barrier coatings are used to enhance the shelf live of sensitive products such as food, medicine or electrical components (e.g. OLEDS). Membranes can be employed to synthesise e.g., Hydrogen, which could be used in the context of renewable energy sources.