Opto-electronic properties of twisted bilayer graphene quantum dots

A. Tiutiunnyk, C. A. Duque, F. J. Caro-Lopera, M. E. Mora-Ramos, J. D. Correa

Resultado de la investigación: Contribución a una revistaArtículoInvestigaciónrevisión exhaustiva

Resumen

The electronic and interband optical properties of vertically coupled stacked graphene quantum dots are investigated using the tight-binding method. Both zigzag and armchair edge configurations are taken into account. In particular, the effect of the geometrical shape (triangular or circle-like) and, most prominently, of the angle of twisting between layers is mainly addressed. The optical response is analyzed from the calculated imaginary part of the dielectric function. It is found that the interband absorption threshold is highly dependent on the dot size and geometry: For armchair triangular bilayer graphene dots the optical gap exhibits a moderate increase for smaller angles of twisting, and the structure behaves as an intermediate to a wide gap semiconductor; whereas zigzag triangular bilayer graphene dots are small gap systems in which the twisting causes the appearance of zero-gap states associated with the variation of HOMO and LUMO states resulting from the breaking of zero-energy degeneracy. In the latter case, it is shown that the low-energy transitions between those states are responsible for the main optical response of the structures which indicates possible applications in the THz optoelectronics. Circular dots are chosen in commensurable configurations and also show stronger low-energy absorption thresholds. A particular feature appearing in this case is the presence of Bravais-Moiré patterns in the two-dimensional probability density distributions for large enough dot radii.

Idioma originalInglés
Páginas (desde-hasta)36-48
Número de páginas13
PublicaciónPhysica E: Low-Dimensional Systems and Nanostructures
Volumen112
DOI
EstadoPublicada - 1 ago 2019

Huella dactilar

Graphite
Electronic properties
Graphene
Semiconductor quantum dots
graphene
twisting
quantum dots
electronics
Energy absorption
Optoelectronic devices
thresholds
energy absorption
Optical properties
configurations
Semiconductor materials
density distribution
Geometry
optical properties
radii
energy

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title = "Opto-electronic properties of twisted bilayer graphene quantum dots",
abstract = "The electronic and interband optical properties of vertically coupled stacked graphene quantum dots are investigated using the tight-binding method. Both zigzag and armchair edge configurations are taken into account. In particular, the effect of the geometrical shape (triangular or circle-like) and, most prominently, of the angle of twisting between layers is mainly addressed. The optical response is analyzed from the calculated imaginary part of the dielectric function. It is found that the interband absorption threshold is highly dependent on the dot size and geometry: For armchair triangular bilayer graphene dots the optical gap exhibits a moderate increase for smaller angles of twisting, and the structure behaves as an intermediate to a wide gap semiconductor; whereas zigzag triangular bilayer graphene dots are small gap systems in which the twisting causes the appearance of zero-gap states associated with the variation of HOMO and LUMO states resulting from the breaking of zero-energy degeneracy. In the latter case, it is shown that the low-energy transitions between those states are responsible for the main optical response of the structures which indicates possible applications in the THz optoelectronics. Circular dots are chosen in commensurable configurations and also show stronger low-energy absorption thresholds. A particular feature appearing in this case is the presence of Bravais-Moir{\'e} patterns in the two-dimensional probability density distributions for large enough dot radii.",
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Opto-electronic properties of twisted bilayer graphene quantum dots. / Tiutiunnyk, A.; Duque, C. A.; Caro-Lopera, F. J.; Mora-Ramos, M. E.; Correa, J. D.

En: Physica E: Low-Dimensional Systems and Nanostructures, Vol. 112, 01.08.2019, p. 36-48.

Resultado de la investigación: Contribución a una revistaArtículoInvestigaciónrevisión exhaustiva

TY - JOUR

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AU - Duque, C. A.

AU - Caro-Lopera, F. J.

AU - Mora-Ramos, M. E.

AU - Correa, J. D.

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AB - The electronic and interband optical properties of vertically coupled stacked graphene quantum dots are investigated using the tight-binding method. Both zigzag and armchair edge configurations are taken into account. In particular, the effect of the geometrical shape (triangular or circle-like) and, most prominently, of the angle of twisting between layers is mainly addressed. The optical response is analyzed from the calculated imaginary part of the dielectric function. It is found that the interband absorption threshold is highly dependent on the dot size and geometry: For armchair triangular bilayer graphene dots the optical gap exhibits a moderate increase for smaller angles of twisting, and the structure behaves as an intermediate to a wide gap semiconductor; whereas zigzag triangular bilayer graphene dots are small gap systems in which the twisting causes the appearance of zero-gap states associated with the variation of HOMO and LUMO states resulting from the breaking of zero-energy degeneracy. In the latter case, it is shown that the low-energy transitions between those states are responsible for the main optical response of the structures which indicates possible applications in the THz optoelectronics. Circular dots are chosen in commensurable configurations and also show stronger low-energy absorption thresholds. A particular feature appearing in this case is the presence of Bravais-Moiré patterns in the two-dimensional probability density distributions for large enough dot radii.

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