Preparation and characterization of sputtered metal oxides and nitrides for optical applications

Sammanfattning: Sputter deposited metal oxide and nitride thin films have been studied for energy-efficient window applications. Coatings, for both static and dynamic control of radiative heat transfer through windows, were optically characterized. As metal base in static solar selective coatings, semi-transparent TiN and ZrN films have been investigated. Cerium oxide based films were studied for use in transparent electrochromic devices capable of modulating solar transmittance.The influence of preparation conditions on the solar selective properties ofTiO2/TiN/TiO2 and ZrO2/ZrN/ZrO2 multilayers were investigated. It was found that a ≈ 2nm thin sacrificial layer of aluminum on top of the nitride film prevented the nitride from oxidizing during preparation and also improved the thermal stability of the multilayers. A significant optical improvement was achieved by growing the ZrN films on crystalline Zr02, prepared at an elevated substrate temperature. The classical Drude model was successfully fitted to the determined optical constants of ZrN films. The Drude analysiswas found to be a useful tool for evaluating the optical performance.Optical and electrochemical characterizations have been performed mostly ofzirconium-cerium oxide films but also of other cerium oxide based films, which are promising as counter electrodes in transparent electrochromic devices. High lithium ion charge capacity and cycling durability, combined with high transmittance of visible light irrespective of the lithium ion content, are the characteristic features of zirconium-cerium oxide coatings. Optical constants of mixed titanium-cerium oxide and zirconium-cerium oxide films with varying compositions have been determined.