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Controlling the Electronic Structures and Properties of in-Plane Transition-Metal Dichalcogenides Quantum Wells.

Wei W, Dai Y, Niu C, Huang B - Sci Rep (2015)

Bottom Line: The true type-II alignment forms due to the coherent lattice and strong interface coupling suggesting the effective separation and collection of excitons.The intrinsic electric polarization enhances the spin-orbital coupling and demonstrates the possibility to achieve topological insulator state and valleytronics in TMD quantum wells.In-plane TMD quantum wells have opened up new possibilities of applications in next-generation devices at nanoscale.

View Article: PubMed Central - PubMed

Affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.

ABSTRACT
In-plane transition-metal dichalcogenides (TMDs) quantum wells have been studied on the basis of first-principles density functional calculations to reveal how to control the electronic structures and the properties. In collection of quantum confinement, strain and intrinsic electric field, TMD quantum wells offer a diverse of exciting new physics. The band gap can be continuously reduced ascribed to the potential drop over the embedded TMD and the strain substantially affects the band gap nature. The true type-II alignment forms due to the coherent lattice and strong interface coupling suggesting the effective separation and collection of excitons. Interestingly, two-dimensional quantum wells of in-plane TMD can enrich the photoluminescence properties of TMD materials. The intrinsic electric polarization enhances the spin-orbital coupling and demonstrates the possibility to achieve topological insulator state and valleytronics in TMD quantum wells. In-plane TMD quantum wells have opened up new possibilities of applications in next-generation devices at nanoscale.

No MeSH data available.


Related in: MedlinePlus

(a) Two-dimensional hexagonal Brillouin zone of the TMD honeycomb lattice; the K-point is folded at the A-point of rectangular Brillouin zone. (b) Polarization field formed in TMD quantum wells. In (b), the arrows show the direction of charge transfer; and shadow regions indicate covalent bonding. The dipole moment is demonstrated by an equation of ql.
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f2: (a) Two-dimensional hexagonal Brillouin zone of the TMD honeycomb lattice; the K-point is folded at the A-point of rectangular Brillouin zone. (b) Polarization field formed in TMD quantum wells. In (b), the arrows show the direction of charge transfer; and shadow regions indicate covalent bonding. The dipole moment is demonstrated by an equation of ql.

Mentions: In this work, we constructed a rectangular unit cell for the calculations, as shown in Fig. 1(a,b). In this model, dimension in a direction is infinite due to the periodic bound condition, while in b direction the length is around 70 Å. As a consequence, the band structures should be calculated in a two-dimensional rectangular Brillouin zone; however, we confirm that the band dispersion relation normal to the zigzag interfaces completely reflects the decisive characters of the band structures and we show the band structures in Γ-X direction. Although the experiments suggested in-plane TMD heterointerfaces in triangular shape with three-fold symmetry, interfacing is along the zigzag direction1011121314 and this asymmetric nature is not necessary to consider in our calculations. It should be pointed out that the zigzag direction of interfacing in TMD quantum wells corresponds to the Γ-K direction of the two-dimensional hexagonal Brillouin zone, as indicated in Fig. 2(a). In consideration of band folding, the K-point of the hexagonal Brillouin zone is folded to the A-point of the rectangular Brillouin zone. In other words, that is why the VBM at Γ- and A-point manifests strong sensitivity to the interaction of constituent TMDs, as found in TMD heterobilayers222327.


Controlling the Electronic Structures and Properties of in-Plane Transition-Metal Dichalcogenides Quantum Wells.

Wei W, Dai Y, Niu C, Huang B - Sci Rep (2015)

(a) Two-dimensional hexagonal Brillouin zone of the TMD honeycomb lattice; the K-point is folded at the A-point of rectangular Brillouin zone. (b) Polarization field formed in TMD quantum wells. In (b), the arrows show the direction of charge transfer; and shadow regions indicate covalent bonding. The dipole moment is demonstrated by an equation of ql.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663467&req=5

f2: (a) Two-dimensional hexagonal Brillouin zone of the TMD honeycomb lattice; the K-point is folded at the A-point of rectangular Brillouin zone. (b) Polarization field formed in TMD quantum wells. In (b), the arrows show the direction of charge transfer; and shadow regions indicate covalent bonding. The dipole moment is demonstrated by an equation of ql.
Mentions: In this work, we constructed a rectangular unit cell for the calculations, as shown in Fig. 1(a,b). In this model, dimension in a direction is infinite due to the periodic bound condition, while in b direction the length is around 70 Å. As a consequence, the band structures should be calculated in a two-dimensional rectangular Brillouin zone; however, we confirm that the band dispersion relation normal to the zigzag interfaces completely reflects the decisive characters of the band structures and we show the band structures in Γ-X direction. Although the experiments suggested in-plane TMD heterointerfaces in triangular shape with three-fold symmetry, interfacing is along the zigzag direction1011121314 and this asymmetric nature is not necessary to consider in our calculations. It should be pointed out that the zigzag direction of interfacing in TMD quantum wells corresponds to the Γ-K direction of the two-dimensional hexagonal Brillouin zone, as indicated in Fig. 2(a). In consideration of band folding, the K-point of the hexagonal Brillouin zone is folded to the A-point of the rectangular Brillouin zone. In other words, that is why the VBM at Γ- and A-point manifests strong sensitivity to the interaction of constituent TMDs, as found in TMD heterobilayers222327.

Bottom Line: The true type-II alignment forms due to the coherent lattice and strong interface coupling suggesting the effective separation and collection of excitons.The intrinsic electric polarization enhances the spin-orbital coupling and demonstrates the possibility to achieve topological insulator state and valleytronics in TMD quantum wells.In-plane TMD quantum wells have opened up new possibilities of applications in next-generation devices at nanoscale.

View Article: PubMed Central - PubMed

Affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.

ABSTRACT
In-plane transition-metal dichalcogenides (TMDs) quantum wells have been studied on the basis of first-principles density functional calculations to reveal how to control the electronic structures and the properties. In collection of quantum confinement, strain and intrinsic electric field, TMD quantum wells offer a diverse of exciting new physics. The band gap can be continuously reduced ascribed to the potential drop over the embedded TMD and the strain substantially affects the band gap nature. The true type-II alignment forms due to the coherent lattice and strong interface coupling suggesting the effective separation and collection of excitons. Interestingly, two-dimensional quantum wells of in-plane TMD can enrich the photoluminescence properties of TMD materials. The intrinsic electric polarization enhances the spin-orbital coupling and demonstrates the possibility to achieve topological insulator state and valleytronics in TMD quantum wells. In-plane TMD quantum wells have opened up new possibilities of applications in next-generation devices at nanoscale.

No MeSH data available.


Related in: MedlinePlus