A comparative study of the UV - optical and structural properties of SiO_2, Al_2O_3 and HfO_2 single layers deposited by reactive evaporation, ion assisted deposition, and plasma ion assisted deposition

摘要

Growing requriements on the otpical and environemtnal stability as well as on the radiation resistance against high power laser radiation especially for optical interference coatings used in the ultraviolet spectral range have to be met by new optimized thin film deposition technologies. For applications in the UV spectral rang ethe number of useful oxide thin film materilas is very limited due to the higher absorption at wavelengths near to the electronic band gap of the materials. Applying ion assisted processes offer the ability to grow dense and stable films, but in each case careful optimization of the deposition process (evaporation rate, substrate temperature, bombarding gas, ion energy, ion current density etc.) has to balance between densification of the layer and the absorption.