A calorimetric study of plasma based thin film deposition applications
Nowadays plasma based processes are widely used for surface modification in a great variety of industrial applications. In many cases plasma based deposition techniques are used to tailor functional thin films on an atomic or molecular scale. The ability to control the plasma process opened new ways in material sciences. One key element during plasma coating is the interaction between the plasma itself and the surrounding surfaces, also called plasma-wall interactions (PWI) or plasma-surface interactions (PSI). It dictates the structure and morphology of the deposited film and has been studied extensively in the last decades. The main interaction relies on particle fluxes which may or may not deposit a significant amount of energy once they hit the surface, binding to the film or getting reflected. Therefore, the characterization of the particles as well as the energy flux reaching the surface is of great importance since it helps to understand fundamental mechanisms and may grant opportunities to improve existing processes for surface modification or develop new ones. In this thesis different plasma based processes used to deposit nanostructured materials are preferably investigated using a calorimetric probe, i.e. a passive thermal probe, which is able to measure the integral energy flux. Combined with additional probe measurements (Langmuir probe, quartz crystal microbalance) and sputter-based simulations (SRIM) a detailed insight of the particle interaction between the plasma and the surface can be obtained. This includes the generation of secondary particles, e.g. secondary electrons which may occur during particle bombardment of a surface. Understanding the energy flux and its origin creates the ability to tailor the different processes to the desired outcome and helps to connect key properties of the final product to certain plasma parameters and discharge conditions.