Microstructure Dictates the Behavior of Plasmons in Nanostructured Ag-Cu Alloy Films

Bandaru, Pravallika and Ummethala, Govind and Malladi, Sai Rama Krishna and Dutta-Gupta, Shourya (2022) Microstructure Dictates the Behavior of Plasmons in Nanostructured Ag-Cu Alloy Films. The Journal of Physical Chemistry C, 126 (37). pp. 15915-15923. ISSN 1932-7447

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Abstract

Surface plasmon (SP) resonances play a vital role in the efficient control of light-matter interaction at the nanoscale beyond the diffraction limit. Alloy plasmonics has opened new avenues for composition-dependent tuning of the plasmonic response. In this study, we demonstrate that phase separation in immiscible alloy systems can be used as an additional degree of freedom in conjunction with the composition to tune the plasmon behavior. The Ag-Cu alloy system is used as a model case to demonstrate the implications of phase separation and composition on both propagating and localized SPs. We use magnetron cosputtering to deposit a metastable FCC solid solution thin film with nanocrystalline grains. Subsequent annealing of the film at 400 °C leads to phase separation and grain growth. The annealed samples exhibit Ag-rich and Cu-rich phases with composition-dependent connectivity. Dispersion of propagating SPs in thin films shows a significant dependence on the composition and annealing conditions. Annealing of the alloy films leads to a strong decrease, by a factor of up to 20%, in the resonance widths of the propagating SPs which is due to a decrease in the imaginary part of the permittivity. Nanoapertures fabricated using focused ion beam (FIB) milling show strong scattering signatures for the metastable and annealed samples. Finally, we demonstrate the site-specific fabrication of nanoapertures in the Cu or Ag domains using ion-secondary electron imaging in FIB. The proposed approach for realizing complex bimetallic nanostructures can potentially be used for realizing multiplexed metasurfaces, active plasmonic platforms, plasmon enhanced catalysis, and site-specific multianalyte sensing. © 2022 American Chemical Society.

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IITH Creators:

IITH Creators	ORCiD
Malladi, Sai Rama Krishna	UNSPECIFIED
Dutta-Gupta, Shourya	UNSPECIFIED

Item Type:

Article

Uncontrolled Keywords:

Annealed samples; Efficient control; Light-matter interactions; Metastables; Nano scale; Nano-apertures; Nano-structured; Site-specific; Surface-plasmon resonance; Thin-films

Subjects:

Materials Engineering > Materials engineering

Divisions:

Department of Material Science Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

29 Sep 2022 09:27

Last Modified:

29 Sep 2022 09:27

URI:

http://raiithold.iith.ac.in/id/eprint/10735