期刊
NANO LETTERS
卷 17, 期 12, 页码 7809-7813出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b04021
关键词
van der Waals heterostructure; interlayer exciton; transition metal dichalcogenides; first-principles calculation
类别
资金
- Laboratory Directed Research and Development program at Sandia National Laboratories
- U.S. Department of Energy's National Nuclear Security Administration [DE-NA-0003525]
- National Science Foundation (NSF) CAREER [DMR-1455346]
Bilayer van der Waals (vdW) heterostructures such as MoS2/WS2 and MoSe2/WSe2 have attracted much attention recently, particularly because of their type II band alignments and the formation of interlayer exciton as the lowest-energy excitonic state. In this work, we calculate the electronic and optical properties of such heterostructures with the first-principles GW+Bethe-Salpeter Equation (BSE) method and reveal the important role of interlayer coupling in deciding the excited-state properties, including the band alignment and excitonic properties. Our calculation shows that due to the interlayer coupling, the low energy excitons can be widely tuned by a vertical gate field. In particular, the dipole oscillator strength and radiative lifetime of the lowest energy exciton in these bilayer heterostructures is varied by over an order of magnitude within a practical external gate field. We also build a simple model that captures the essential physics behind this tunability and allows the extension of the ab initio results to a large range of electric fields. Our work clarifies the physical picture of interlayer excitons in bilayer vdW heterostructures and predicts a wide range of gate-tunable excited-state properties of 2D optoelectronic devices.
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