Effects of environmental and exciton screening in single-walled carbon nanotubes

Adamyan, V. M.; Smyrnov, Oleksii A.; Tishchenko, S. V.

doi:10.1088/1742-6596/129/1/012012

“…The main reason for the change in the spectrum is the nonlocal dielectric screening associated with the inhomogeneous dielectric environment of the TMD ML. This results in a screened Coulomb potential (Cudazzo et al, 2011;Keldysh, 1979;Rytova, 1967) with a distance dependence that deviates strongly from the usual 1/r form, as detailed below, and also introduced in the context of carbon nanotubes (Adamyan et al, 2008;Ando, 2010;Deslippe et al, 2009;Wang et al, 2005).…”

Section: Exciton and Continuum States In Optics And Transportmentioning

confidence: 99%

Colloquium : Excitons in atomically thin transition metal dichalcogenides

Wang

¹

,

Chernikov

²

,

Glazov

³

et al. 2018

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Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. Here we review recent progress in our understanding of the excitonic properties in monolayer TMDs and lay out future challenges. We focus on the consequences of the strong direct and exchange Coulomb interaction, discuss exciton-light interaction and effects of other carriers and excitons on electron-hole pairs in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observed in applied electric and magnetic fields is summarized.

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“…The main reason for the change in the spectrum is the nonlocal dielectric screening associated with the inhomogeneous dielectric environment of the TMD ML. This results in a screened Coulomb potential (Cudazzo et al, 2011;Keldysh, 1979;Rytova, 1967) with a distance dependence that deviates strongly from the usual 1/r form, as detailed below, and also introduced in the context of carbon nanotubes (Adamyan et al, 2008;Ando, 2010;Deslippe et al, 2009;Wang et al, 2005).…”

Section: Exciton and Continuum States In Optics And Transportmentioning

confidence: 99%

Excitons in atomically thin transition-metal dichalcogenides

Chernikov

¹

,

Berkelbach

²

,

Hill

³

et al. 2014

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Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. Here we review recent progress in our understanding of the excitonic properties in monolayer TMDs and lay out future challenges. We focus on the consequences of the strong direct and exchange Coulomb interaction, discuss exciton-light interaction and effects of other carriers and excitons on electron-hole pairs in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observed in applied electric and magnetic fields is summarized.

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“…[41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] Environmental effects were theoretically discussed by assuming a dielectric constant 25,26,29,30,56) or using more elaborate models. [57][58][59][60][61] In this paper, we study environmental effects based on a k Á p scheme by exactly taking account of the image effect within a continuum model. The paper is organized as follows: In §2 a brief review is given on the k Á p description of electronic states, the Coulomb potential in the presence of cylindrical dielectric medium, and a method of calculation of exciton states.…”

Section: Introductionmentioning

confidence: 99%

Environment Effects on Excitons in Semiconducting Carbon Nanotubes

Ando

¹

2010

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Effects of environmental dielectric screening on excitons in carbon nanotubes are studied within a k Á p scheme and a continuum model. They are shown to be sensitive to the effective distance between the nanotube and the dielectric medium relative to the diameter. For material surrounding the nanotube, the band gap decreases with the increase of the dielectric constant, but the energy of the ground exciton exhibits only a slight decrease for effective distance comparable to interlayer spacing of bulk graphite. The binding energy of excited exciton states disappears rapidly. For dielectric material inside the nanotube, effects are much weaker and excited exciton states remain as bound states even for very large dielectric constant.

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Effects of environmental and exciton screening in single-walled carbon nanotubes

Cited by 10 publications

References 18 publications

Colloquium : Excitons in atomically thin transition metal dichalcogenides

Colloquium : Excitons in atomically thin transition metal dichalcogenides

Excitons in atomically thin transition-metal dichalcogenides

Environment Effects on Excitons in Semiconducting Carbon Nanotubes

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