Improved selective properties of SiO2/TiNxOy-Al tandem absorbers effected by tempering

TiNxOy-Al and SiO2/TiNxOy-Al selective absorbers, prepared in an ARE (Activated Reactive Evaporation) deposition process, have been investigated in respect of effects induced by heat treatment. Samples were exposed to residual gas atmospheres of 10-4hPa and 10hPa respectively, in a temperature range of 225 degree(s)C - 470 degree(s)C. Three different processes were observed. They were analyzed investigating optical properties, element concentration and structure of the compounds. Reflectance measurements are in agreement with calculations of the spectral reflection from known optical constants.