Design und Herstellung selektiver Dünnschichtabsorber auf Silberinselbasis

The combination of a metal island film with a dielectric multilayer represents a novel approach for preparation of spectrally selective absorbers. Metal island films show exceptional optical properties caused by the optical excitation of surface plasmon modes. The plasmon resonance frequency depends on the size and shape of the islands and is influenced by the deposition parameters. The first type of samples represents a silver island film in an ultra thin Al2O3 film. We analyzed these samples by means of spectrophotometry. The recorded spectra allow the calculation of the optical constants of the silver island films. These show a maximum absorptance up to 40%. Finally, we incorporated ultrathin metal-dielectriccomposite films on a silver/alumina basis into multilayer stacks to design tailored spectrally selective absorber coatings. The stack absorptance comes close to 100%.