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Robust Direct Bandgap Characteristics of One- and Two-Dimensional ReS2.

Yu ZG, Cai Y, Zhang YW - Sci Rep (2015)

Bottom Line: Two-dimensional (2D) transition-metal dichalcogenides (TMDs), most notably, MoS2 and WS2, have attracted significant attention due to their sizable and direct bandgap characteristics.In addition, the direct bandgap of ReS2 nanoribbons is only weakly dependent on their width.These robust characteristics strongly suggest that ReS2 has great potential for applications in optoelectronic nanodevices.

View Article: PubMed Central - PubMed

Affiliation: Institute of High Performance Computing, Singapore 138632, Singapore.

ABSTRACT
Two-dimensional (2D) transition-metal dichalcogenides (TMDs), most notably, MoS2 and WS2, have attracted significant attention due to their sizable and direct bandgap characteristics. Although several interesting MoS2 and WS2-based optoelectronic devices have been reported, their processability and reproducibility are limited since their electrical properties are strongly dependent of the number of layers, strain and sample sizes. It is highly desirable to have a robust direct bandgap TMD, which is insensitive to those factors. In this work, using density functional theory, we explore the effects of layer number, strain and ribbon width on the electronic properties of ReS2, a new member in the TMD family. The calculation results reveal that for monolayer ReS2, the nature (direct versus indirect) and magnitude of its bandgap are insensitive to strain. Importantly, the predicted bandgap and also charge carrier mobilities are nearly independent of the number of layers. In addition, the direct bandgap of ReS2 nanoribbons is only weakly dependent on their width. These robust characteristics strongly suggest that ReS2 has great potential for applications in optoelectronic nanodevices.

No MeSH data available.


Related in: MedlinePlus

The calculated results of size-dependent band structure of RY1-NRs.
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f5: The calculated results of size-dependent band structure of RY1-NRs.

Mentions: Beyond ML ReS2, the electronic properties of ReS2 NRs remain largely unexplored, which are crucial for their applications in nanodevices. Here, we focus on the size effect on their electronic properties. It is well-known that NRs (1D) have different electronic properties compared to mono- or multi-layer (2D) form. The edge atoms of NRs introduce new flat energy levels at both valence and conduction band edges, narrowing the band gap accordingly. Here, we further investigate the quantum size effect on the bandgap of ReS2 NRs (RY1-series). Our calculation results show that RY1-NRs are semiconductors with a director bandgap, and the bandgap increases with increasing ribbon width (N), and converges to 0.92 eV as shown in Fig. 5. In our models, N = 1, 2, 3, and 4 corresponds to a width of 13.27, 18.27, 20.58, 26.40 and 38.19 Å, respectively. It should be noted that for N = 1, which corresponds to a RY1-NR with a width of 13.27 Å, the k-space conduction band minimum and valence band maximum shift away from Γ point. But the NR still retains the nature of direct bandgap, which may be caused by the narrow width and symmetry-breaking in the FBZ.


Robust Direct Bandgap Characteristics of One- and Two-Dimensional ReS2.

Yu ZG, Cai Y, Zhang YW - Sci Rep (2015)

The calculated results of size-dependent band structure of RY1-NRs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562306&req=5

f5: The calculated results of size-dependent band structure of RY1-NRs.
Mentions: Beyond ML ReS2, the electronic properties of ReS2 NRs remain largely unexplored, which are crucial for their applications in nanodevices. Here, we focus on the size effect on their electronic properties. It is well-known that NRs (1D) have different electronic properties compared to mono- or multi-layer (2D) form. The edge atoms of NRs introduce new flat energy levels at both valence and conduction band edges, narrowing the band gap accordingly. Here, we further investigate the quantum size effect on the bandgap of ReS2 NRs (RY1-series). Our calculation results show that RY1-NRs are semiconductors with a director bandgap, and the bandgap increases with increasing ribbon width (N), and converges to 0.92 eV as shown in Fig. 5. In our models, N = 1, 2, 3, and 4 corresponds to a width of 13.27, 18.27, 20.58, 26.40 and 38.19 Å, respectively. It should be noted that for N = 1, which corresponds to a RY1-NR with a width of 13.27 Å, the k-space conduction band minimum and valence band maximum shift away from Γ point. But the NR still retains the nature of direct bandgap, which may be caused by the narrow width and symmetry-breaking in the FBZ.

Bottom Line: Two-dimensional (2D) transition-metal dichalcogenides (TMDs), most notably, MoS2 and WS2, have attracted significant attention due to their sizable and direct bandgap characteristics.In addition, the direct bandgap of ReS2 nanoribbons is only weakly dependent on their width.These robust characteristics strongly suggest that ReS2 has great potential for applications in optoelectronic nanodevices.

View Article: PubMed Central - PubMed

Affiliation: Institute of High Performance Computing, Singapore 138632, Singapore.

ABSTRACT
Two-dimensional (2D) transition-metal dichalcogenides (TMDs), most notably, MoS2 and WS2, have attracted significant attention due to their sizable and direct bandgap characteristics. Although several interesting MoS2 and WS2-based optoelectronic devices have been reported, their processability and reproducibility are limited since their electrical properties are strongly dependent of the number of layers, strain and sample sizes. It is highly desirable to have a robust direct bandgap TMD, which is insensitive to those factors. In this work, using density functional theory, we explore the effects of layer number, strain and ribbon width on the electronic properties of ReS2, a new member in the TMD family. The calculation results reveal that for monolayer ReS2, the nature (direct versus indirect) and magnitude of its bandgap are insensitive to strain. Importantly, the predicted bandgap and also charge carrier mobilities are nearly independent of the number of layers. In addition, the direct bandgap of ReS2 nanoribbons is only weakly dependent on their width. These robust characteristics strongly suggest that ReS2 has great potential for applications in optoelectronic nanodevices.

No MeSH data available.


Related in: MedlinePlus