Metallic Properties of the Si(111) − 5 × 2 − Au Surface from Infrared Plasmon Polaritons and Ab Initio Theory

Hötzel, Fabian; Seino, K.; Huck, Christian; Skibbe, Olaf; Bechstedt, F.; Pucci, Annemarie

doi:10.1021/acs.nanolett.5b01279

Cited by 28 publications

(37 citation statements)

References 41 publications

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“…Altogether, the present calculations for the KK model agree considerably better with the measured data than the calculations based on the EBH structure. The preference for the KK model is in agreement with experimental results from surface x-ray diffraction [10], infrared spectroscopy [11], and reflectance anisotropy spectroscopy [14].…”

Section: First-principles Calculationssupporting

confidence: 85%

“…A possible realization is the material system Au/Si(111), where, depending on the Au coverage and the substrate temperature, one-or two-dimensional ordered Au patterns can be achieved, whose reconstructions are characterized by the (5 × 2) and ( √ 3 × √ 3) periodicity, respectively [2,3]. The Au-(5 × 2)/Si(111) reconstruction with its onedirectional Au-induced chains has been the subject of extended experimental and theoretical investigations [4][5][6][7][8][9][10][11] for many years. In spite of all these studies, the atomic arrangement of this reconstruction has given rise to recent disputes in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Vibration eigenmodes of the Au- (5×2) /Si(111) surface studied by Raman spectroscopy and first-principles calculations

et al. 2016

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Ordered submonolayers of adsorbate atoms on semiconductor surfaces constitute a playground for electronic correlation effects, which are tightly connected to the local atomic arrangement and the corresponding vibration eigenmodes. We report on a study of the vibration eigenmodes of Au-covered Si(111) surfaces with (5 × 2) reconstruction using polarized Raman spectroscopy and first-principles calculations. Upon Au coverage, the vibration eigenmodes of the clean reconstructed Si(111)-(7 × 7) surface are quenched and replaced by new eigenmodes, determined by the Au-(5 × 2) reconstruction. Several polarization-dependent surface eigenmodes emerge in the spectral range from 25 to 120 cm −1 , with the strongest ones at 29, 51, and 106 cm −1. In our first-principles calculations we have determined the vibration frequencies, the corresponding elongation patterns, and the Raman intensities for two different structure models currently discussed in the literature. The best agreement with the experimental results is achieved for a model with 0.7 monolayer coverage and seven Au atoms per unit cell, proposed by S. G. Kwon and M. H. Kang [Phys. Rev. Lett. 113, 086101 (2014)].

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Section: First-principles Calculationssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Vibration eigenmodes of the Au- (5×2) /Si(111) surface studied by Raman spectroscopy and first-principles calculations

et al. 2016

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“…Taking the measured width as lifetime would mean that the plasmonic excitation is highly overdamped and plasmonic excitations would not exist. This is in sharp contrast to plasmons (at 125 meV) in comparable systems, where mean free paths exceeding 200 nm were observed [116]. Therefore, the FWHM at k = 0 must be the convolution of instrumental resolution in reciprocal space and in energy of the spectrometer, possibly also with a contribution caused by the short interaction time of the electron scattering process.…”

Section: Measured Peak Width Of Plasmon Lossesmentioning

confidence: 87%

Plasmons in one and two dimensions

Pfnür¹,

Tegenkamp²,

Vattuone³

2017

Preprint

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Plasmons in low-dimensional systems respresent an important tool for coupling energy into nanostructures and the localization of energy on the scale of only a few nanometers. Contrary to ordinary surface plasmons of metallic bulk materials, their dispersion goes to zero in the long wavelength limit, thus covering a broad range of energies from terahertz to near infrared, and from mesoscopic wavelengths down to just a few nanometers. Using specific and most characteristic examples, we review first the properties of plasmons in two-dimensional (2D) metallic layers from an experimental point of view. As demonstrated, tuning of their dispersion is possible by changes of charge carrier concentration in the partially filled 2D conduction bands, but for the relativistic electron gas like in graphene only in the long wavelength limit. For short wavelengths, on the other hand, the dispersion turns out to be independent of the position of the Fermi level with respect to the Dirac point. A linear dispersion, seen under the latter conditions in graphene, can also be obtained in non-relativistic electron gases by coupling between 2D and 3D electronic systems. As a well investigated example, the acoustic surface plasmons in Shockley surface states, coupled with the bulk electronic system, are discussed. Also the introduction of anisotropy, e.g. by regular arrays of steps, seems to result in linearization (and to partial localization of the plasmons normal to the steps, depending on wavelengths). In quasi-one dimensional (1D) systems, such as arrays of gold chains on regularly stepped Si surfaces, only the dispersion is 1D, whereas shape and slope of the dispersion curves depend on the 2D distribution of charge within each terrace and on coupling between wires on different terraces. In other words, the form of the confining quasi-1D potential enters directly into the 1D plasmon dispersion and gives new opportunities for tuning.

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“…Moreover, the atomic structure of the Si(111)5 × 2-Au surface itself had been elusive with various structural models of different Au concentration proposed 15 , 16 , 23 – 26 , 29 , 30 . A conclusive structural model was only recently proposed by Kwon and Kang 26 (hereafter, KK model), which was then solidly supported by quite a few updated experiments 11 , 12 , 26 , 28 , 31 – 33 . Within the KK model, the characteristic ×2 reconstruction of the atomic chains is realized by the intrinsic ×2 arrangement of Au atoms (see Fig.…”

Section: Introductionmentioning

confidence: 85%

Structural and electronic effects of adatoms on metallic atomic chains in Si(111)5 × 2-Au

Hwan

Kwon

Kang

et al. 2018

Sci Rep

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We investigate the effects of native Si adatoms on structural and electronic properties of the Si(111)5 × 2-Au surface, a representative one-dimensional metal-chain system, by means of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. High-resolution STM images of relatively long adatom-free chain segments evidence directly the inherent ×2 reconstruction, which is the essential part of a recently proposed structural model based on a renewed Au coverage of 0.7 monolayer. On the other hand, STM images for chain segments of different lengths reveal that the structural distortion induced by Si adatoms is confined in neighboring unit cells, in good agreement with DFT calculations based on that model. Si adatoms greatly affect the metallic bands of Au chains, one of which becomes fully occupied and represents a tightly confined electronic state to the distortion around Si adatoms, potentially forming short insulating segments within metallic chains. This finding provides an atomic-scale understanding of the observed gradual metal-insulator transition and atomic-scale phase separation induced by Si adatoms.

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Metallic Properties of the Si(111) − 5 × 2 − Au Surface from Infrared Plasmon Polaritons and Ab Initio Theory

Cited by 28 publications

References 41 publications

Vibration eigenmodes of the Au- (5×2) /Si(111) surface studied by Raman spectroscopy and first-principles calculations

Vibration eigenmodes of the Au- (5×2) /Si(111) surface studied by Raman spectroscopy and first-principles calculations

Plasmons in one and two dimensions

Structural and electronic effects of adatoms on metallic atomic chains in Si(111)5 × 2-Au

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