Effect of roughness and nanoporosity on optical properties of black and reflective Al films prepared by magnetron sputtering
Effect of roughness and nanoporosity on optical properties of black and reflective Al films prepared by magnetron sputtering
Hruška, P.; More-Chevalier, J.; Novotný, M.; Čížek, J.; Melikhova, O.; Fekete, L.; Poupon, M.; Bulíř, J.; Volfová, L.; Butterling, M.; Liedke, M. O.; Wagner, A.; Fitl, P.
In this work, a comparison of the microstructure of black and classic reflective aluminum films is provided. The N2 concentration during the magnetron sputtering deposition has a key impact on the growth process and final moth-eye-like morphology of black Al films. The study of films with thickness ~1.5 μm and ~8 μm and fully developed microstructure enabled us to clarify the origin of different optical properties of black and reflective Al. Atomic force microscopy measurements showed high roughnesses for both types of films leading to light scattering from their surface. In the case of black Al, the incident light is absorbed in a fractallike nanoporous surface. Less than 3 % of the intensity in the wavelength range from 190 nm to 1200 nm is reflected. Positronium formation in columnar nanopores with a diameter of 4 – 5 Å was observed by positron annihilation lifetime spectroscopy. The nanoporosity rather than the roughness is the key feature of black films compared to reflective ones.
Keywords: black aluminum; magnetron sputtering; atomic force microscopy; spectrophotometric reflectance; positron annihilation spectroscopy
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- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- P-ELBE
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 32137) publication
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Journal of Alloys and Compounds 872(2021), 159744
DOI: 10.1016/j.jallcom.2021.159744
Cited 12 times in Scopus
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