Thickness-dependent free-electron relaxation time of Au thin films in near-infrared region

Zhang, Mingying; Wang, Ziyi; Zhang, Tian-Ning; Zhang, Yun; Zhang, Rongjun; Chen, Xin; Sun, Yun; Zheng, Yuanzhou; Wang, Song-You; Chen, Liang‐Yao

doi:10.1117/1.jnp.10.033009

Cited by 11 publications

(5 citation statements)

References 33 publications

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“…Thus, it has been shown that for polycrystalline metal films, the electron scattering at surfaces and grain boundaries contributes strongly to losses [9,10] affecting the complex dielectric function [11]. The exhaustive study of the structural and optical properties of various materials, including traditional plasmonic metals (Au, Ag, Cu, and Al) [12][13][14] and alternative plasmonic materials (TiN, TCO and others) [15], has been reported with a considerable interest shown in thin films (with the thickness of less than 50 nm) for which a change in the optical properties has been observed as a function of their thickness under constant evaporation regimes [16][17][18]. Furthermore, the temperature-dependent optical properties of single-and polycrystalline gold thin films were also recently studied [19].…”

Section: Introductionmentioning

confidence: 99%

Optical constants and structural properties of thin gold films

Yakubovsky¹,

Arsenin²,

Stebunov³

et al. 2017

Opt. Express

309

153

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We report a comprehensive experimental study of optical and electrical properties of thin polycrystalline gold films in a wide range of film thicknesses (from 20 to 200 nm). Our experimental results are supported by theoretical calculations based on the measured morphology of the fabricated gold films. We demonstrate that the dielectric function of the metal is determined by its structural morphology. Although the fabrication process can be absolutely the same for different films, the dielectric function can strongly depend on the film thickness. Our studies show that the imaginary part of the dielectric function of gold, which is responsible for optical losses, rapidly increases as the film thickness decreases for thicknesses below 80 nm. At the same time, we do not observe a noticeable dependence of optical constants on the film thickness for thicker samples. These findings establish design rules for thin-film plasmonic and nanophotonic devices.

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Section: Introductionmentioning

confidence: 99%

Optical constants and structural properties of thin gold films

Yakubovsky¹,

Arsenin²,

Stebunov³

et al. 2017

Opt. Express

309

153

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“…Indeed, our calculated electron effective mass in Co encapsulated Cu film is much larger than in bare Cu film. Moreover, the relaxation time ( τ ) in thin metallic films is also a function of film thickness 50 . For thinner films, increase in successive collisions lead to decrease in relaxation time.…”

Section: Resultsmentioning

confidence: 99%

Effect of encapsulation on electronic transport properties of nanoscale Cu(111) films

Shinde

Adiga

Pandian

et al. 2019

Sci Rep

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The stiff compromise between reliability and conductivity of copper interconnects used in sub-nanometer nodes has brought into focus the choice of encapsulation material. While reliability was the primary driver so far, herein, we investigate how electronic conductivity of Cu(111) thin films is influenced by the encapsulation material using density functional theory and Boltzmann transport equation. Atomically thin 2D materials, namely conducting graphene and insulating graphane both retain the conductivity of Cu films whereas partially hydrogenated graphene (HGr) results in reduction of surface density of states and a reduction in Cu film conductivity. Among transition metal elements, we find that atoms in Co encapsulation layer, which essentially act as magnetic impurities, serve as electron scattering centres resulting in a decrease in conductivity by at least 15% for 11 nm thick Cu film. On the other hand, Mo, Ta, and Ru have more favorable effect on conductivity when compared to Co. The cause of decrease in conductivity for Co and HGr is discussed by investigating the electronic band structure and density of states. Our DFT calculations suggest that pristine graphene sheet is a good encapsulation material for advanced Cu interconnects both from chemical protection and conductivity point of view.

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“…Generally, a lot of SPR-based techniques are available to determine the geometrical and optical constants of thin metal films [ 18 , 19 , 20 ]. For their dispersion characterization, the spectral techniques such ellipsometry [ 21 , 22 , 23 ], reflectometry [ 24 ], and SPR-based reflectometry [ 25 , 26 ] are possible. We prefer to measure the dielectric function by a simple and cost-effective method compared to standard approaches like spectral ellipsometry, and, in addition, our motivation is application of the same configuration we use in sensing.…”

Section: Introductionmentioning

confidence: 99%

Surface Plasmon Resonance Based Measurement of the Dielectric Function of a Thin Metal Film

Chlebus

Chylek

Ciprián

et al. 2018

Sensors

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A spectral method based on surface plasmon resonance (SPR) in air is used to measure the dielectric function of a thin metal film. The method utilizes the spectral dependence of the ratio of the reflectances of p- and s-polarized waves measured in the Kretschmann configuration at different angles of incidence. By processing these dependences in the vicinity of a dip, or equivalently near the resonance wavelength, and using the dispersion characteristics of a metal film according to a proposed physical model, the real and imaginary parts of the dielectric function of the metal can be determined. The corresponding dielectric function of the metal is obtained by a least squares method for such a thickness minimizing the difference between the measured and theoretical dependence of the resonance wavelength on the the angle of incidence. The feasibility of the method is demonstrated in measuring the dielectric function of a gold film of an SPR structure comprising an SF10 glass prism and a gold coated SF10 slide with an adhesion film of chromium. The dielectric function according to the Drude–Lorentz model with two additional Lorentzian terms was determined in a wavelength range from 534 to 908 nm, and the results show that the gold film is composed of homogenous and rough layers with thicknesses 42.8 nm and 2.0 nm, respectively. This method is particularly useful in measuring the thickness and dielectric function of a thin metal film of SPR structures, directly in the Kretschmann configuration.

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Thickness-dependent free-electron relaxation time of Au thin films in near-infrared region

Cited by 11 publications

References 33 publications

Optical constants and structural properties of thin gold films

Optical constants and structural properties of thin gold films

Effect of encapsulation on electronic transport properties of nanoscale Cu(111) films

Surface Plasmon Resonance Based Measurement of the Dielectric Function of a Thin Metal Film

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