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A Unified Understanding of the Thickness-Dependent Bandgap Transition in Hexagonal Two-Dimensional Semiconductors

Title
A Unified Understanding of the Thickness-Dependent Bandgap Transition in Hexagonal Two-Dimensional Semiconductors
Authors
Kang, J[Kang, Joongoo]Zhang, LJ[Zhang, Lijun]Wei, SH[Wei, Su-Huai]
DGIST Authors
Kang, J[Kang, Joongoo]
Issue Date
2016-02-18
Citation
Journal of Physical Chemistry Letters, 7(4), 597-602
Type
Article
Article Type
Article
Keywords
Band-Gap TransitionCalculationsCrystal SymmetryEnergy GapFirst-Principles CalculationHexagonal Boron Nitride (H-BN)Hexagonal LatticeHigh-Symmetry PointsLayered SemiconductorsSymmetry AnalysisTransition-Metals DichalcogenidesTransition-MetalssTwo-Dimensional Semiconductors
ISSN
1948-7185
Abstract
Many important layered semiconductors, such as hexagonal boron nitride (hBN) and transition-metal dichalcogenides (TMDs), are derived from a hexagonal lattice. A single layer of such hexagonal semiconductors generally has a direct bandgap at the high-symmetry point K, whereas it becomes an indirect, optically inactive semiconductor as the number of layers increases to two or more. Here, taking hBN and MoS2 as examples, we reveal the microscopic origin of the direct-to-indirect bandgap transition of hexagonal layered materials. Our symmetry analysis and first-principles calculations show that the bandgap transition arises from the lack of the interlayer orbital couplings for the band-edge states at K, which are inherently weak because of the crystal symmetries of hexagonal layered materials. Therefore, it is necessary to judiciously break the underlying crystal symmetries to design more optically active, multilayered semiconductors from hBN or TMDs. © 2016 American Chemical Society.
URI
http://hdl.handle.net/20.500.11750/2550
DOI
10.1021/acs.jpclett.5b02687
Publisher
American Chemical Society
Files:
There are no files associated with this item.
Collection:
Emerging Materials ScienceETC1. Journal Articles


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