Characterization and formation mechanism of black Au films deposited under varied Ar gas pressures

Abstract Nanoporous black Au (B-Au) films were fabricated under varied Ar gas pressures (2, 60, and 100 Pa) via thermal evaporation. Film structures and properties were assessed with a consistent Au atom quantity of approximately 1.6 × 10−2 mol m−2. Irrespective of the deposition pressure, all sampl...

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Bibliographic Details
Main Authors: Kazuto Takada, Midori Kawamura, Takayuki Kiba, Yoshio Abe, Mikito Ueda, Matej Mičušik, Martin Hruška, Michal Novotný, Přemysl Fitl
Format: Article
Language:English
Published: Springer 2025-07-01
Series:Discover Materials
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Online Access:https://doi.org/10.1007/s43939-025-00324-5
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Summary:Abstract Nanoporous black Au (B-Au) films were fabricated under varied Ar gas pressures (2, 60, and 100 Pa) via thermal evaporation. Film structures and properties were assessed with a consistent Au atom quantity of approximately 1.6 × 10−2 mol m−2. Irrespective of the deposition pressure, all samples displayed a black appearance devoid of metallic luster, resulting in almost zero specular and diffuse reflections. The highest optical absorption, reaching 99.8%, occurred at 2 Pa deposition pressure. The film density decreased notably with increasing pressure, enabling the creation of films with a density below 1.0 g/cm3—equivalent to 5% of the filling factor of bulk Au—by carefully controlling the deposition pressure. FESEM observation and XRD analyses revealed gas-phase metal particle formation in the preparation of B-Au films, similar to our previous study on B-Ag films. In addition, when deposited on a quartz crystal microbalance (QCM), the B-Au film exhibited enhanced response of the QCM sensor to ethanol vapor. The applicability of this technology to gas sensors has been confirmed.
ISSN:2730-7727