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The Role of Optical Phonon Confinement in the Infrared Dielectric Response of III–V Superlattices

Matson, Joseph R. ; Alam, Md Nazmul ; Varnavides, Georgios ; Sohr, Patrick ; Knight, Sean LU ; Darakchieva, Vanya LU ; Stokey, Megan ; Schubert, Mathias LU orcid ; Said, Ayman and Beechem, Thomas , et al. (2023) In Advanced Materials
Abstract

Polar dielectrics are key materials of interest for infrared (IR) nanophotonic applications due to their ability to host phonon-polaritons that allow for low-loss, subdiffractional control of light. The properties of phonon-polaritons are limited by the characteristics of optical phonons, which are nominally fixed for most “bulk” materials. Superlattices composed of alternating atomically thin materials offer control over crystal anisotropy through changes in composition, optical phonon confinement, and the emergence of new modes. In particular, the modified optical phonons in superlattices offer the potential for so-called crystalline hybrids whose IR properties cannot be described as a simple mixture of the bulk constituents. To date,... (More)

Polar dielectrics are key materials of interest for infrared (IR) nanophotonic applications due to their ability to host phonon-polaritons that allow for low-loss, subdiffractional control of light. The properties of phonon-polaritons are limited by the characteristics of optical phonons, which are nominally fixed for most “bulk” materials. Superlattices composed of alternating atomically thin materials offer control over crystal anisotropy through changes in composition, optical phonon confinement, and the emergence of new modes. In particular, the modified optical phonons in superlattices offer the potential for so-called crystalline hybrids whose IR properties cannot be described as a simple mixture of the bulk constituents. To date, however, studies have primarily focused on identifying the presence of new or modified optical phonon modes rather than assessing their impact on the IR response. This study focuses on assessing the impact of confined optical phonon modes on the hybrid IR dielectric function in superlattices of GaSb and AlSb. Using a combination of first principles theory, Raman, FTIR, and spectroscopic ellipsometry, the hybrid dielectric function is found to track the confinement of optical phonons, leading to optical phonon spectral shifts of up to 20 cm−1. These results provide an alternative pathway toward designer IR optical materials.

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organization
publishing date
type
Contribution to journal
publication status
in press
subject
keywords
confinement, infrared, phonons, spectroscopy
in
Advanced Materials
publisher
John Wiley & Sons Inc.
external identifiers
  • pmid:38039437
  • scopus:85178479693
ISSN
0935-9648
DOI
10.1002/adma.202305106
language
English
LU publication?
yes
id
75ee93e3-3e78-4bab-84e1-d399ae863df2
date added to LUP
2024-01-02 15:54:13
date last changed
2024-04-17 15:08:39
@article{75ee93e3-3e78-4bab-84e1-d399ae863df2,
  abstract     = {{<p>Polar dielectrics are key materials of interest for infrared (IR) nanophotonic applications due to their ability to host phonon-polaritons that allow for low-loss, subdiffractional control of light. The properties of phonon-polaritons are limited by the characteristics of optical phonons, which are nominally fixed for most “bulk” materials. Superlattices composed of alternating atomically thin materials offer control over crystal anisotropy through changes in composition, optical phonon confinement, and the emergence of new modes. In particular, the modified optical phonons in superlattices offer the potential for so-called crystalline hybrids whose IR properties cannot be described as a simple mixture of the bulk constituents. To date, however, studies have primarily focused on identifying the presence of new or modified optical phonon modes rather than assessing their impact on the IR response. This study focuses on assessing the impact of confined optical phonon modes on the hybrid IR dielectric function in superlattices of GaSb and AlSb. Using a combination of first principles theory, Raman, FTIR, and spectroscopic ellipsometry, the hybrid dielectric function is found to track the confinement of optical phonons, leading to optical phonon spectral shifts of up to 20 cm<sup>−1</sup>. These results provide an alternative pathway toward designer IR optical materials.</p>}},
  author       = {{Matson, Joseph R. and Alam, Md Nazmul and Varnavides, Georgios and Sohr, Patrick and Knight, Sean and Darakchieva, Vanya and Stokey, Megan and Schubert, Mathias and Said, Ayman and Beechem, Thomas and Narang, Prineha and Law, Stephanie and Caldwell, Joshua D.}},
  issn         = {{0935-9648}},
  keywords     = {{confinement; infrared; phonons; spectroscopy}},
  language     = {{eng}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Advanced Materials}},
  title        = {{The Role of Optical Phonon Confinement in the Infrared Dielectric Response of III–V Superlattices}},
  url          = {{http://dx.doi.org/10.1002/adma.202305106}},
  doi          = {{10.1002/adma.202305106}},
  year         = {{2023}},
}