Determination of thickness-dependent damping constant and plasma frequency for ultrathin Ag and Au films: nanoscale dielectric function

Herrera, Luis Joaquín Mendoza; Tebaldi, Myrian; Scaffardi, Lucia; Schinca, Daniel Carlos

doi:10.1039/d2cp04286j

Cited by 9 publications

(9 citation statements)

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“…[15]. At the same time, our results are in disagreement with the conclusion [ 16,33 ] that the plasma frequency should decrease when the thickness of metal film becomes smaller than 15 nm. This conclusion was supported by some phenomenological theory.…”

Section: Resultscontrasting

confidence: 99%

“…Hall measurements provide unambiguously the electron concentration of metal films and do not dependent on a model used (in contrast to processing of optical data). Hence, we believe that the disagreement with the previous works [ 16,33 ] is connected to the properties of Au films deposited on MoS 2 , namely, their roughness and substrate conductivity.…”

Section: Resultscontrasting

confidence: 60%

“…[9] but in stark contrast with the results obtained on UTGFs fabricated on MoS 2 substrates [16] where it was found that the plasma frequency decreases when thickness falls below 6 nm. [33] This discrepancy is not surprising as the presence of a conductive MoS 2 substrate could significantly change the extracted values of plasma frequency due to the resistive coupling through the conductive sublayer. [34,35] It is worth noting that the Drude parameters of the films fabricated in Manchester and Barcelona are roughly the same despite slightly different methods of sample preparation, see Figure 4.…”

Section: Resultsmentioning

confidence: 99%

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Optical Constants and Optical Anisotropy of Ultrathin Gold Films

Akolzina,

Kravets,

Berdyugin

et al. 2023

Advanced Photonics Research

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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.

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Section: Resultscontrasting

confidence: 99%

Section: Resultscontrasting

confidence: 60%

Section: Resultsmentioning

confidence: 99%

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Optical Constants and Optical Anisotropy of Ultrathin Gold Films

Akolzina,

Kravets,

Berdyugin

et al. 2023

Advanced Photonics Research

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“…Confinement-induced nonlocality is the remarkable intrinsic property of the in-plane EM response of TD systems. 24 It is this nonlocality that enables a variety of new quantum phenomena in ultrathin films, including thickness-controlled plasma frequency red shift, 10,31 lowtemperature plasma frequency dropoff, 32 plasmon mode degeneracy lifting and spontaneous emission enhancement, 19 directional negative refractivity, 17 absorption-transmission switching under controlled exciton-plasmon coupling, 18 a series of quantum-optical, 14 magneto-optical 22 and radiative heat transfer effects 33,34 as well as quantum electronic transitions that are normally forbidden. 35 The confinement-induced nonlocal EM response comes from the Keldysh-Rytova (KR) pairwise interaction potential.…”

Section: Introductionmentioning

confidence: 99%

Confinement-induced nonlocality and casimir force in transdimensional systems

Bondarev,

Pugh,

Rodriguez-Lopez

et al. 2023

Phys. Chem. Chem. Phys.

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“…[ 12–20 ] The strong vertical quantum confinement makes these modes distinct from those of conventional thin films commonly described either by 2D or by 3D material properties with boundary conditions on their top and bottom interfaces. [ 21–29 ] Their properties can be understood in terms of the confinement‐induced nonlocal Drude electromagnetic (EM) response theory proposed [ 15 ] and verified both experimentally [ 10,30 ] and computationally [ 3,31 ] recently. The EM response nonlocality was earlier reported experimentally to be a remarkable intrinsic property of quantum‐confined metallic nanostructures.…”

Section: Introductionmentioning

confidence: 92%

Far‐ and Near‐Field Heat Transfer in Transdimensional Plasmonic Film Systems

Biehs

Bondarev

2023

Advanced Optical Materials

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to a larger number of layers approaching the 3D bulk material properties. [11,14] They offer controlled light confinement and large tailorability of their optical properties due to their thickness-dependent localized surface plasmon (SP) modes. [12][13][14][15][16][17][18][19][20] The strong vertical quantum confinement makes these modes distinct from those of conventional thin films commonly described either by 2D or by 3D material properties with boundary conditions on their top and bottom interfaces. [21][22][23][24][25][26][27][28][29] Their properties can be understood in terms of the confinement-induced nonlocal Drude electromagnetic (EM) response theory proposed [15] and verified both experimentally [10,30] and computationally [3,31] recently. The EM response nonlocality was earlier reported experimentally to be a remarkable intrinsic property of quantum-confined metallic nanostructures. [32,33] It is this nonlocality that enables a variety of new quantum phenomena in ultrathin TD plasmonic film systems, including the thickness-controlled plasma frequency red shift, [10,15] the low-temperature plasma frequency dropoff, [30] the SP mode degeneracy lifting, [14,34] a series of quantum-optical [13] and nonlocal magneto-optical effects, [16] as well as quantum electronic transitions that are normally forbidden. [12,35,36] The confinement-induced nonlocal Drude EM response theory is built on the Keldysh-Rytova (KR) pairwise electron interaction potential [15] (and so referred to as the KR model in what follows for brevity). The KR interaction potential takes into account the vertical electron confinement due to the presence of substrate and superstrate materials with dielectric permittivities much less than that of the film. [37,38] For ultrathin films the KR potential is much stronger than the Coulomb interaction potential. [37] It turns into the Coulomb potential with film thickness increase, suggesting the film thickness as a parameter to control the nonlocal optical response of TD materials. The nonlocal KR model is unique in that it covers the entire thickness range from atomically thin films to conventional films of the order of a few optical wavelengths in thickness. [10,14] We perform a comparative study of the far-field and near-field heat transfer processes in the metallic TD film systems using the nonlocal KR model and the standard local Drude EM response model (a 'workhorse' routinely used in plasmonics). We show that the nonlocal KR model results in the greater Woltersdorff length (the film thickness at which its thermal emission is maximal) in the far-field regime and predicts larger film thicknesses at which the near-field heat transfer starts being dominated by surface plasmons, as compared to those resulted from A confinement-induced nonlocal electromagnetic response model is applied to study radiative heat transfer processes in transdimensional plasmonic film systems. The results are compared to the standard local Drude model routinely used in plasmonics. The former predicts greater Woltersdor...

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Determination of thickness-dependent damping constant and plasma frequency for ultrathin Ag and Au films: nanoscale dielectric function

Abstract: This paper is devoted to determine an analytical expression for the thickness dependent complex dielectric function for the case of Ag and Au thin films. Free and bound electron contributions...

Cited by 9 publications

References 50 publications

Optical Constants and Optical Anisotropy of Ultrathin Gold Films

Optical Constants and Optical Anisotropy of Ultrathin Gold Films

Confinement-induced nonlocality and casimir force in transdimensional systems

Far‐ and Near‐Field Heat Transfer in Transdimensional Plasmonic Film Systems

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