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Ambardar S, Withers ZH, Liu J, Lai X, Albagami A, Zhukova A, Fabris Capelli P, Sahoo PK, Voronine DV. Quantum plasmonic two-dimensional WS 2-MoS 2 heterojunction. Nanoscale 2023; 15:7318-7328. [PMID: 37017120 DOI: 10.1039/d3nr00861d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Two-dimensional heterostructures have recently gained broad interest due to potential applications in optoelectronic devices. Their reduced dimensionality leads to novel physical effects beyond conventional bulk electronics. However, the optical properties of the 2D lateral heterojunctions have not been completely characterized due to the limited spatial resolution, requiring nano-optical techniques beyond the diffraction limit. Here, we investigate lateral monolayer WS2-MoS2 heterostructures in a plasmonic Au-Au tip-substrate picocavity using subdiffraction limited tip-enhanced photoluminescence (TEPL) spectroscopy with sub-nanometer tip-sample distance control. We observed more than 3 orders of magnitude PL enhancement by placing a plasmonic Au-coated tip at the resonantly excited heterojunction. We developed a theoretical model of the quantum plasmonic 2D heterojunction, where tunneling of hot electrons between the Au tip and MoS2 leads to the quenching of the MoS2 PL, while simultaneously increasing the WS2 PL, in contrast to the non-resonant reverse transfer. Our simulations show good agreement with the experiments, revealing a range of parameters and enhancement factors corresponding to the switching between the classical and quantum regimes. The controllable photoresponse of the 2D heterojunction can be used in novel nanodevices.
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Affiliation(s)
- Sharad Ambardar
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA.
| | - Zachary H Withers
- Department of Physics, Stony Brook University, Stony Brook, NY 11790, USA
| | - Jiru Liu
- Department of Physics, Texas A&M University, College Station, TX 77840, USA
| | - Xiaoyi Lai
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Abdullah Albagami
- Department of Physics, King Saud University, Riyadh 11362, Kingdom of Saudi Arabia
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Alina Zhukova
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | | | - Prasana K Sahoo
- Materials Science Centre, India Institute of Technology, Kharagpur, India
| | - Dmitri V Voronine
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA.
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
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Kunin A, Chernov S, Bakalis J, Li Z, Cheng S, Withers ZH, White MG, Schönhense G, Du X, Kawakami RK, Allison TK. Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS_{2}. Phys Rev Lett 2023; 130:046202. [PMID: 36763432 DOI: 10.1103/physrevlett.130.046202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
Using time- and angle-resolved photoemission, we present momentum- and energy-resolved measurements of exciton coupling in monolayer WS_{2}. We observe strong intravalley coupling between the B_{1s} exciton and A_{n>1} states. Our measurements indicate that the dominant valley depolarization mechanism conserves the exciton binding energy and momentum. While this conservation is consistent with Coulomb exchange-driven valley depolarization, we do not observe a momentum or energy dependence to the depolarization rate as would be expected for the exchange-based mechanism.
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Affiliation(s)
- Alice Kunin
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Sergey Chernov
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Jin Bakalis
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Ziling Li
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Shuyu Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Zachary H Withers
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
| | - Michael G White
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Gerd Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, D-55099 Mainz, Germany
| | - Xu Du
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
| | - Roland K Kawakami
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Thomas K Allison
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
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Abstract
Two-dimensional transition metal dichalcogenides provide flexible platforms for nanophotonic engineering due to their exceptional mechanical and optoelectronic properties. For example, continuous band gap tunability has been achieved in 2D TMDs by elastic strain engineering. Localized elastic deformations in nanobubbles behave as "artificial atoms" with a spatially varying band gap resulting in funnelling of excitons and photocarriers. Here we present a new method of nanobubble fabrication in monolayer 2D lateral heterostructures using high temperature superacid treatment. We fabricated MoS2 and WS2 nanobubbles and performed near-field imaging with nanoscale resolution using tip-enhanced photoluminescence (TEPL) spectroscopy. TEPL nanoimaging revealed the coupling between MoS2 and WS2 nanobubbles with a large synergistic PL enhancement due to the plasmonic tip, hot electrons, and exciton funnelling. We investigated the contributions of different enhancement mechanisms, and developed a quantum plasmonic model, in good agreement with the experiments. Our work opens new avenues in exploration of novel nanophotonic coupling schemes.
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Affiliation(s)
- Sharad Ambardar
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA.
| | - Rana Kamh
- Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA
| | - Zachary H Withers
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Prasana K Sahoo
- Materials Science Centre, India Institute of Technology, Kharagpur, India
| | - Dmitri V Voronine
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA.
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
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