Comparative study of the deposition of highly reflectant metal thin films by ionized PVD techniques

The degree of ionization during Physical Vapor Deposition (PVD) plays a critical role on the final surface quality of the deposited coatings. In this work a comparative study of metal thin films (Al, Cu, Ag) deposited by conventional DC-Magnetron Sputtering (DCMS) and highly ionized techniques such as Filtered Cathodic Vacuum Arc (FCVA) and high power impulse magnetron sputtering (HiPIMS) was performed. The final scope of the study is aimed to optimize the deposition parameters to achieve higher specular reflectance as this have a critical influence in the yield of solar plants based on concentrated solar power. In this regard, the optical constants of the deposited films were modeled departing from ellipsometry data. A comparison of the experimental reflectance with that obtained after optical simulation was also carried out. The achieved optical performance of the films was further compared to the structural properties resulting from different deposition techniques. Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA)was applied to explore the potential oxidation of the films during deposition. Surface morphological changes were explored by Scanning Electron Microscopy (SEM). In addition, Atomic Force Microscopy (AFM) measurements at different deposition times allowed exploring the dynamics of the growth mechanism of the films.