Ultrathin 2 nm gold as impedance-matched absorber for infrared light

Niklas Luhmann, Dennis Høj, Markus Piller, Hendrik Kähler, Miao-Hsuan Chien, Robert G. West, Ulrik Lund Andersen, Silvan Schmid*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Thermal detectors are a cornerstone of infrared and terahertz technology due to their broad spectral range. These detectors call for efficient absorbers with a broad spectral response and minimal thermal mass. A common approach is based on impedance-matching the sheet resistance of a thin metallic film to half the free-space impedance. Thereby, one can achieve a wavelength-independent absorptivity of up to 50%. However, existing absorber films typically require a thickness of the order of tens of nanometers, which can significantly deteriorate the response of a thermal transducer. Here, we present the application of ultrathin gold (2 nm) on top of a surfactant layer of oxidized copper as an effective infrared absorber. An almost wavelength-independent and long-time stable absorptivity of 47(3)%, ranging from 2 μm to 20 μm, can be obtained. The presented absorber allows for a significant improvement of infrared/terahertz technologies in general and thermal detectors in particular.
Original languageEnglish
Article number2161
JournalNature Communications
Issue number1
Number of pages7
Publication statusPublished - 2020

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