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Yu Y, Yu Y, Huang L, Peng H, Xiong L, Cao L. Giant Gating Tunability of Optical Refractive Index in Transition Metal Dichalcogenide Monolayers. NANO LETTERS 2017; 17:3613-3618. [PMID: 28505462 DOI: 10.1021/acs.nanolett.7b00768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report that the refractive index of transition metal dichacolgenide (TMDC) monolayers, such as MoS2, WS2, and WSe2, can be substantially tuned by >60% in the imaginary part and >20% in the real part around exciton resonances using complementary metal-oxide-semiconductor (CMOS) compatible electrical gating. This giant tunablility is rooted in the dominance of excitonic effects in the refractive index of the monolayers and the strong susceptibility of the excitons to the influence of injected charge carriers. The tunability mainly results from the effects of injected charge carriers to broaden the spectral width of excitonic interband transitions and to facilitate the interconversion of neutral and charged excitons. The other effects of the injected charge carriers, such as renormalizing bandgap and changing exciton binding energy, only play negligible roles. We also demonstrate that the atomically thin monolayers, when combined with photonic structures, can enable the efficiencies of optical absorption (reflection) tuned from 40% (60%) to 80% (20%) due to the giant tunability of the refractive index. This work may pave the way toward the development of field-effect photonics in which the optical functionality can be controlled with CMOS circuits.
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Affiliation(s)
| | | | | | - Haowei Peng
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19405, United States
| | - Liwei Xiong
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, Wuhan Institute of Technology , Wuhan, 430205, P. R. China
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Zhong WP, Belić MR, Malomed BA, Zhang Y, Huang T. Spatiotemporal accessible solitons in fractional dimensions. Phys Rev E 2016; 94:012216. [PMID: 27575132 DOI: 10.1103/physreve.94.012216] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Indexed: 11/07/2022]
Abstract
We report solutions for solitons of the "accessible" type in globally nonlocal nonlinear media of fractional dimension (FD), viz., for self-trapped modes in the space of effective dimension 2<D≤3 with harmonic-oscillator potential whose strength is proportional to the total power of the wave field. The solutions are categorized by a combination of radial, orbital, and azimuthal quantum numbers (n,l,m). They feature coaxial sets of vortical and necklace-shaped rings of different orders, and can be exactly written in terms of special functions that include Gegenbauer polynomials, associated Laguerre polynomials, and associated Legendre functions. The validity of these solutions is verified by direct simulations. The model can be realized in various physical settings emulated by FD spaces; in particular, it applies to excitons trapped in quantum wells.
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Affiliation(s)
- Wei-Ping Zhong
- Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300, China.,Texas A&M University at Qatar, P.O. Box 23874 Doha, Qatar
| | | | - Boris A Malomed
- Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.,Laboratory of Nonlinear-Optical Informatics, ITMO University, St. Petersburg 197101, Russia
| | - Yiqi Zhang
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049, China
| | - Tingwen Huang
- Texas A&M University at Qatar, P.O. Box 23874 Doha, Qatar
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Yu Y, Yu Y, Cai Y, Li W, Gurarslan A, Peelaers H, Aspnes DE, Van de Walle CG, Nguyen NV, Zhang YW, Cao L. Exciton-dominated Dielectric Function of Atomically Thin MoS2 Films. Sci Rep 2015; 5:16996. [PMID: 26598075 PMCID: PMC4657050 DOI: 10.1038/srep16996] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/22/2015] [Indexed: 12/18/2022] Open
Abstract
We systematically measure the dielectric function of atomically thin MoS2
films with different layer numbers and demonstrate that excitonic effects play a
dominant role in the dielectric function when the films are less than
5–7 layers thick. The dielectric function shows an anomalous dependence
on the layer number. It decreases with the layer number increasing when the films
are less than 5–7 layers thick but turns to increase with the layer
number for thicker films. We show that this is because the excitonic effect is very
strong in the thin MoS2 films and its contribution to the dielectric
function may dominate over the contribution of the band structure. We also extract
the value of layer-dependent exciton binding energy and Bohr radius in the films by
fitting the experimental results with an intuitive model. The dominance of excitonic
effects is in stark contrast with what reported at conventional materials whose
dielectric functions are usually dictated by band structures. The knowledge of the
dielectric function may enable capabilities to engineer the light-matter
interactions of atomically thin MoS2 films for the development of novel
photonic devices, such as metamaterials, waveguides, light absorbers, and light
emitters.
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Affiliation(s)
- Yiling Yu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Yifei Yu
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Yongqing Cai
- Institute of High Performance Computing, A*STAR, Singapore 138632
| | - Wei Li
- Semiconductor and Dimensional Metrology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Alper Gurarslan
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA.,Department of Fiber and Polymer Science, North Carolina State University, Raleigh, NC 27695, USA
| | - Hartwin Peelaers
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - David E Aspnes
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | | | - Nhan V Nguyen
- Semiconductor and Dimensional Metrology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Yong-Wei Zhang
- Institute of High Performance Computing, A*STAR, Singapore 138632
| | - Linyou Cao
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA.,Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
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Evaluating a Special Class of Two-Body Integrals through Maple's Integral Routine Extension. Comput Sci Eng 2014. [DOI: 10.1109/mcse.2013.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Horta-Piñeres S, Escorcia-Salas GE, Mikhailov ID, Sierra-Ortega J. Trion X+ in vertically coupled type II quantum dots in threading magnetic field. NANOSCALE RESEARCH LETTERS 2012; 7:532. [PMID: 23013605 PMCID: PMC3563483 DOI: 10.1186/1556-276x-7-532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 09/12/2012] [Indexed: 06/01/2023]
Abstract
We analyze the energy spectrum of a positively charged exciton confined in a semiconductor heterostructure formed by two vertically coupled, axially symmetrical type II quantum dots located close to each other. The electron in the structure is mainly located inside the dots, while the holes generally move in the exterior region close to the symmetry axis. The solutions of the Schrödinger equation are obtained by a variational separation of variables in the adiabatic limit. Numerical results are shown for bonding and anti-bonding lowest-lying of the trion states corresponding to the different quantum dots morphologies, dimensions, separation between them, thicknesses of the wetting layers, and the magnetic field strength.
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Affiliation(s)
- Sindi Horta-Piñeres
- Group of Investigation in Condensed Matter Theory, Universidad del Magdalena, Santa Marta, AA 731, Colombia
- Universidad de Sucre, Sincelejo, AA 406, Colombia
| | | | - Ilia D Mikhailov
- Universidad Industrial de Santander, Bucaramanga, AA 678, Colombia
| | - José Sierra-Ortega
- Group of Investigation in Condensed Matter Theory, Universidad del Magdalena, Santa Marta, AA 731, Colombia
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Lefebvre P, Christol P, Mathieu H. Unified formulation of excitonic absorption spectra of semiconductor quantum wells, superlattices, and quantum wires. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:17308-17315. [PMID: 10008340 DOI: 10.1103/physrevb.48.17308] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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He XF. Excitons in anisotropic solids: The model of fractional-dimensional space. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:2063-2069. [PMID: 9997475 DOI: 10.1103/physrevb.43.2063] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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