Laterally modulating carrier concentration by ion irradiation in CdO thin films for mid-IR plasmonics
Laterally modulating carrier concentration by ion irradiation in CdO thin films for mid-IR plasmonics
This report demonstrates tunable carrier densities in CdO thin films through local ion irradiation, providing lateral control of mid-IR optical properties. Ion-solid interactions produce donor-like defects that boost electron concentrations from the practical minimum of 2.5 × 1019 cm−3 to a maximum of 2.5 × 1020 cm−3 by metered ion exposure. This range is achieved using He, N, Ar, or Au ions at 1–2.8 MeV; when normalized by displacements per atom, all ion species produce comparable results. Since CdO is well-described by the Drude model, irradiation-tuned carrier densities directly alter the infrared dielectric function, and in turn, mid-infrared optical properties. Further, it is demonstrated that by combining irradiation with traditional lithography, CdO films expose to ions in the presence of 3-µm thick, patterned photoresist exhibit lateral carrier density profiles with ≈400-nm resolution. Scanning near-field optical microscopy reveals sharp optical interfaces with almost no companion contrast in surface morphology, microstructure, or crystallinity. Finally, CdO lateral homostructures supporting surface plasmon polaritons (SPPs) are demonstrated whose dispersion relation can be tuned through periodic patterning in a monolithic platform by simple nanofabrication. Numerical simulations show these polaritons result from strong coupling between excitations at CdO plasma frequencies and SPPs supported by the platinum substrate.
Cleri, Angela J.
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He, Mingze
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Tolchin, Maxwell J.
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Gubbin, Christopher
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Lang, Eric
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Hattar, Khalid
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De Liberato, Simone
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Caldwell, Joshua D.
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Maria, Jon-Paul
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Cleri, Angela J.
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He, Mingze
0e9cf440-ee5d-483e-a1e4-097398bcc58d
Tolchin, Maxwell J.
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Gubbin, Christopher
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Lang, Eric
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Hattar, Khalid
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De Liberato, Simone
5942e45f-3115-4027-8653-a82667ed8473
Caldwell, Joshua D.
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Maria, Jon-Paul
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Cleri, Angela J., He, Mingze, Tolchin, Maxwell J., Gubbin, Christopher, Lang, Eric, Hattar, Khalid, De Liberato, Simone, Caldwell, Joshua D. and Maria, Jon-Paul
(2024)
Laterally modulating carrier concentration by ion irradiation in CdO thin films for mid-IR plasmonics.
Advanced Optical Materials.
(doi:10.1002/adom.202401009).
Abstract
This report demonstrates tunable carrier densities in CdO thin films through local ion irradiation, providing lateral control of mid-IR optical properties. Ion-solid interactions produce donor-like defects that boost electron concentrations from the practical minimum of 2.5 × 1019 cm−3 to a maximum of 2.5 × 1020 cm−3 by metered ion exposure. This range is achieved using He, N, Ar, or Au ions at 1–2.8 MeV; when normalized by displacements per atom, all ion species produce comparable results. Since CdO is well-described by the Drude model, irradiation-tuned carrier densities directly alter the infrared dielectric function, and in turn, mid-infrared optical properties. Further, it is demonstrated that by combining irradiation with traditional lithography, CdO films expose to ions in the presence of 3-µm thick, patterned photoresist exhibit lateral carrier density profiles with ≈400-nm resolution. Scanning near-field optical microscopy reveals sharp optical interfaces with almost no companion contrast in surface morphology, microstructure, or crystallinity. Finally, CdO lateral homostructures supporting surface plasmon polaritons (SPPs) are demonstrated whose dispersion relation can be tuned through periodic patterning in a monolithic platform by simple nanofabrication. Numerical simulations show these polaritons result from strong coupling between excitations at CdO plasma frequencies and SPPs supported by the platinum substrate.
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Advanced Optical Materials - 2024 - Cleri - Laterally Modulating Carrier Concentration by Ion Irradiation in CdO Thin Films
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e-pub ahead of print date: 24 September 2024
Identifiers
Local EPrints ID: 494451
URI: http://eprints.soton.ac.uk/id/eprint/494451
ISSN: 2195-1071
PURE UUID: be73e943-aefa-4135-85d8-8bff40ded217
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Date deposited: 08 Oct 2024 16:47
Last modified: 09 Oct 2024 01:50
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Contributors
Author:
Angela J. Cleri
Author:
Mingze He
Author:
Maxwell J. Tolchin
Author:
Christopher Gubbin
Author:
Eric Lang
Author:
Khalid Hattar
Author:
Joshua D. Caldwell
Author:
Jon-Paul Maria
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