Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit
Abstract Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by i...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2022-11-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-022-23119-7 |
| _version_ | 1811223571301662720 |
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| author | Mahsa Haddadi. M Bamadev Das Jeeyoon Jeong Sunghwan Kim Dai-Sik Kim |
| author_facet | Mahsa Haddadi. M Bamadev Das Jeeyoon Jeong Sunghwan Kim Dai-Sik Kim |
| author_sort | Mahsa Haddadi. M |
| collection | DOAJ |
| description | Abstract Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conductivity, typically in the sub-Angstrom range for good metals if bulk conductivity is maintained throughout. This makes it extremely difficult to obtain substantial absorption from thin metal films, in contrast to 2D materials such as graphene. Luckily, however, from a practical point of view, metal conductivity is drastically reduced as the film becomes sub-100 nm, to make it a race between the thinnest possible metal thickness experimentally achievable vs the conductivity reduction. Here, we demonstrate a near-50% absorption at a gold film thickness of 6.5 nm, with conductivity much reduced from the bulk value, down to the range of 106 Siemens per meter. Studying the effect of the substrate thickness, we found that the common cover glass, with its thickness much smaller than the wavelength, achieves symmetric absorption of 44%, implying that a pseudo-free-standing limit is achieved. Our work may find applications in infrared sensing as in bolometers and biomedical sensing using microwaves. |
| first_indexed | 2024-04-12T08:35:08Z |
| format | Article |
| id | doaj.art-6a82e8971648448cac3ca78ba4d3ecae |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-12T08:35:08Z |
| publishDate | 2022-11-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-6a82e8971648448cac3ca78ba4d3ecae2022-12-22T03:40:02ZengNature PortfolioScientific Reports2045-23222022-11-011211710.1038/s41598-022-23119-7Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limitMahsa Haddadi. M0Bamadev Das1Jeeyoon Jeong2Sunghwan Kim3Dai-Sik Kim4Department of Physics and Quantum Photonics Institute, Ulsan National Institute of Science and Technology (UNIST)Department of Physics and Quantum Photonics Institute, Ulsan National Institute of Science and Technology (UNIST)Department of Physics, Institute of Quantum Convergence Technology, Kangwon National UniversityDepartment of Physics and Quantum Photonics Institute, Ulsan National Institute of Science and Technology (UNIST)Department of Physics and Quantum Photonics Institute, Ulsan National Institute of Science and Technology (UNIST)Abstract Electromagnetic absorbers based on ultra-thin metallic film are desirable for many applications such as plasmonics, metamaterials, and long-wavelength detectors. A metallic film will achieve a maximum 50% of electromagnetic wave absorption, frequency independent, at a thickness defined by its conductivity, typically in the sub-Angstrom range for good metals if bulk conductivity is maintained throughout. This makes it extremely difficult to obtain substantial absorption from thin metal films, in contrast to 2D materials such as graphene. Luckily, however, from a practical point of view, metal conductivity is drastically reduced as the film becomes sub-100 nm, to make it a race between the thinnest possible metal thickness experimentally achievable vs the conductivity reduction. Here, we demonstrate a near-50% absorption at a gold film thickness of 6.5 nm, with conductivity much reduced from the bulk value, down to the range of 106 Siemens per meter. Studying the effect of the substrate thickness, we found that the common cover glass, with its thickness much smaller than the wavelength, achieves symmetric absorption of 44%, implying that a pseudo-free-standing limit is achieved. Our work may find applications in infrared sensing as in bolometers and biomedical sensing using microwaves.https://doi.org/10.1038/s41598-022-23119-7 |
| spellingShingle | Mahsa Haddadi. M Bamadev Das Jeeyoon Jeong Sunghwan Kim Dai-Sik Kim Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit Scientific Reports |
| title | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
| title_full | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
| title_fullStr | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
| title_full_unstemmed | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
| title_short | Near-maximum microwave absorption in a thin metal film at the pseudo-free-standing limit |
| title_sort | near maximum microwave absorption in a thin metal film at the pseudo free standing limit |
| url | https://doi.org/10.1038/s41598-022-23119-7 |
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