Optical Constants and Optical Anisotropy of Ultrathin Gold Films
Continuous and homogeneous thin gold films are fabricated on Si–SiO2 substrates using an additional seed layer based on Cu oxide or oxidized Cu. The optical properties of these gold films with thicknesses from 3 to 50 nm are studied with the help of variable angle spectroscopic ellipsometry. The opt...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Wiley-VCH
2024-01-01
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| Series: | Advanced Photonics Research |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/adpr.202300238 |
| _version_ | 1797363973743443968 |
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| author | Diana Akolzina Vasyl G. Kravets Alexey I. Berdyugin Alexander N. Grigorenko |
| author_facet | Diana Akolzina Vasyl G. Kravets Alexey I. Berdyugin Alexander N. Grigorenko |
| author_sort | Diana Akolzina |
| collection | DOAJ |
| description | Continuous and homogeneous thin gold films are fabricated on Si–SiO2 substrates using an additional seed layer based on Cu oxide or oxidized Cu. The optical properties of these gold films with thicknesses from 3 to 50 nm are studied with the help of variable angle spectroscopic ellipsometry. The optical constants and the dielectric functions of thin Au films in the wavelength range of 240–1700 nm are extracted by fitting measured ellipsometric data using the Fresnel isotropic and anisotropic models. By applying the Drude approximation to the infrared range, values of the plasma frequency ωp and relaxation time τ are obtained as a function of film thickness. It is found that plasma frequency ωp of the gold films is mostly constant in the thickness range of 3–50 nm with an average being close to the bulk value ωp ≈ 8.45 eV. The relaxation time decreases dramatically from the bulk values of τ ≈ 14 fs to τ ≈ 2 fs for gold films of 3 nm in an agreement with the confinement effect. It is established that the thinnest gold films (≈3 nm) are described better by an anisotropic layer and the underlying reasons for such optical anisotropy are discussed. |
| first_indexed | 2024-03-08T16:28:42Z |
| format | Article |
| id | doaj.art-d4cf8be971214a898b0cd7b83f9bd414 |
| institution | Directory Open Access Journal |
| issn | 2699-9293 |
| language | English |
| last_indexed | 2024-03-08T16:28:42Z |
| publishDate | 2024-01-01 |
| publisher | Wiley-VCH |
| record_format | Article |
| series | Advanced Photonics Research |
| spelling | doaj.art-d4cf8be971214a898b0cd7b83f9bd4142024-01-06T12:33:20ZengWiley-VCHAdvanced Photonics Research2699-92932024-01-0151n/an/a10.1002/adpr.202300238Optical Constants and Optical Anisotropy of Ultrathin Gold FilmsDiana Akolzina0Vasyl G. Kravets1Alexey I. Berdyugin2Alexander N. Grigorenko3Department of Physics and Astronomy University of Manchester Manchester M13 9PL UKDepartment of Physics and Astronomy University of Manchester Manchester M13 9PL UKDepartment of Physics and Astronomy University of Manchester Manchester M13 9PL UKDepartment of Physics and Astronomy University of Manchester Manchester M13 9PL UKContinuous and homogeneous thin gold films are fabricated on Si–SiO2 substrates using an additional seed layer based on Cu oxide or oxidized Cu. The optical properties of these gold films with thicknesses from 3 to 50 nm are studied with the help of variable angle spectroscopic ellipsometry. The optical constants and the dielectric functions of thin Au films in the wavelength range of 240–1700 nm are extracted by fitting measured ellipsometric data using the Fresnel isotropic and anisotropic models. By applying the Drude approximation to the infrared range, values of the plasma frequency ωp and relaxation time τ are obtained as a function of film thickness. It is found that plasma frequency ωp of the gold films is mostly constant in the thickness range of 3–50 nm with an average being close to the bulk value ωp ≈ 8.45 eV. The relaxation time decreases dramatically from the bulk values of τ ≈ 14 fs to τ ≈ 2 fs for gold films of 3 nm in an agreement with the confinement effect. It is established that the thinnest gold films (≈3 nm) are described better by an anisotropic layer and the underlying reasons for such optical anisotropy are discussed.https://doi.org/10.1002/adpr.202300238confinement effectsoptical anisotropyoptical constantsplasma frequenciesultrathin gold |
| spellingShingle | Diana Akolzina Vasyl G. Kravets Alexey I. Berdyugin Alexander N. Grigorenko Optical Constants and Optical Anisotropy of Ultrathin Gold Films Advanced Photonics Research confinement effects optical anisotropy optical constants plasma frequencies ultrathin gold |
| title | Optical Constants and Optical Anisotropy of Ultrathin Gold Films |
| title_full | Optical Constants and Optical Anisotropy of Ultrathin Gold Films |
| title_fullStr | Optical Constants and Optical Anisotropy of Ultrathin Gold Films |
| title_full_unstemmed | Optical Constants and Optical Anisotropy of Ultrathin Gold Films |
| title_short | Optical Constants and Optical Anisotropy of Ultrathin Gold Films |
| title_sort | optical constants and optical anisotropy of ultrathin gold films |
| topic | confinement effects optical anisotropy optical constants plasma frequencies ultrathin gold |
| url | https://doi.org/10.1002/adpr.202300238 |
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