Infrared absorbance of silicene and germanene

Bechstedt, F.; Matthes, Lars; Gori, Paola; Pulci, Olivia

doi:10.1063/1.4731626

Cited by 147 publications

(127 citation statements)

References 22 publications

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“…Intriguingly, the presence of the buckling, which is responsible for the sp 2 -sp 3 character of FSS, does not lift the degeneracy nor the linear dispersion of bands at the K point in the Brillouin zone, so that FSS shows an absorbance A(ω) → πα (with α the fine-structure constant) in the limit of ω → 0. Other features are a first absorption peak at 1.6 eV due to a van Hove singularity in the joint density of state and a main peak at about 4 eV [14].…”

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confidence: 99%

“…For the unsupported 4 × 4 case (dotted red curve in Fig. 3), the sharp interband peak at 4 eV characterizing FSS absorbance [14] evolves to a broader feature, still centered at 4 eV, indicating a modified band structure. Conversely, the van Hove feature at about 1.6 eV at the M point of the Brillouin zone for FSS is still present, as shown in the inset of Fig.…”

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confidence: 99%

“…We finally evaluate the optical properties using the Yambo software [18]. We focus on the optical absorbance at normal incidence in the visible-near UV range, which for a silicene/Ag(111) slab reads [14]:…”

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Optical response and ultrafast carrier dynamics of the silicene-silver interface

Cinquanta¹,

Fratesi

Conte

et al. 2015

Phys. Rev. B

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We report a combined experimental and theoretical study of the optical response of epitaxial silicene on silver. The silicene/Ag(111) ultraviolet-visible absorption spectra, which turn out to be strongly nonadditive, are analyzed in the framework of ab initio calculations. Electronic transitions involving silver states are found to provide huge contributions to the optical absorption of silicene, compatible with a strong Si-Ag hybridization. The results are independent of the specific silicene configuration and are also worked out for thin amorphous silicon. This points to a dimensionality-driven peculiar dielectric response of the two-dimensional-silicon/silver interface, which is confirmed by means of transient-reflectance spectroscopy. The latter shows a metalliclike relaxation time, hence demonstrating the effects of the strong hybridization arising in silicene/Ag (111) Recently, the integration of silicene in field-effect transistors (FET) [1] opened new challenges in the comprehension of the chemical and physical properties of this elusive two-dimensional (2D) allotropic form of silicon. Intense efforts have been devoted to the study of the epitaxial silicene/Ag(111) system in order to elucidate the presence of massless Dirac fermion in analogy with graphene [2,3]. Although recent experiments report on the linear dispersive bands [4], strong hybridization effects have been invoked as responsible for the disruption of π and π * bands in silicene superstructures on silver [5][6][7][8][9]. In this framework, the measured ambipolar effect in silicene-based FET characterized by a relatively high mobility when Ag is withdrawn, points to a complex physics at the silicene-silver interface, demanding a deeper comprehension of its details on the atomic scale.The present paper aims at elucidating the role of the Ag(111) metallic support in determining the physical properties of the Si/Ag (2D) interface, by means of optical techniques combined with theoretical calculations. In particular we show that interface states built up by mixed silicon and silver wave functions have a striking impact on the optical response of the low-dimensional Si/Ag system.

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Optical response and ultrafast carrier dynamics of the silicene-silver interface

Cinquanta¹,

Fratesi

Conte

et al. 2015

Phys. Rev. B

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“…In particular, it is viewed as a new type of atomic-layered material with outstanding properties such as the zero effective mass at the Dirac point and infrared absorbance optical spectra [22][23][24]. Experimentally, single layer silicene (buckled) [25][26][27][28][29][30][31][32][33][34][35][36] and silicene nanoribbons (SiNRs) [25,27] have been synthesized on Ag substrate.…”

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Thermoelectric properties of atomically thin silicene and germanene nanostructures

et al. 2014

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The thermoelectric properties in one-and two-dimensional silicon and germanium structures have been investigated using first-principles density functional techniques and linear response for the thermal and electrical transport. We have considered here the two-dimensional silicene and germanene, together with nanoribbons of different widths. For the nano ribbons, we have also investigated the possibility of nano structuring these systems by mixing silicon and germanium. We found that the figure of merit at room temperature of these systems is remarkably high, up to 2.5.

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“…However, it has been demonstrated for graphene that for energies up to 3 eV the influence of many particle effects is negligible. [37][38][39] The optical spectra show that for two adsorbed oxygen atoms a band gap of 0.5 eV is opened due to the symmetry breaking and increased sp 3 character of the carbon states. A semiconducting behaviour is confirmed for this configuration by previous calculations of the band structure and density of states.…”

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A first-principles investigation of the optical spectra of oxidized graphene

Singh

Kaloni

Schwingenschlögl

2013

Applied Physics Letters

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The electronic and optical properties of mono, di, tri, and tetravacancies in graphene are studied in comparison to each other, using density functional theory. In addition, oxidized monovacancies are considered for different oxygen concentrations. Pristine graphene is found to be more absorptive than any defect configuration at low energy. We demonstrate characteristic differences in the optical spectra of the various defects for energies up to 3 eV. This makes it possible to quantify by optical spectroscopy the ratios of the defect species present in a sample.

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Infrared absorbance of silicene and germanene

Cited by 147 publications

References 22 publications

Optical response and ultrafast carrier dynamics of the silicene-silver interface

Optical response and ultrafast carrier dynamics of the silicene-silver interface

Thermoelectric properties of atomically thin silicene and germanene nanostructures

A first-principles investigation of the optical spectra of oxidized graphene

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