1
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Rota MB, Krieger TM, Buchinger Q, Beccaceci M, Neuwirth J, Huet H, Horová N, Lovicu G, Ronco G, Covre da Silva SF, Pettinari G, Moczała-Dusanowska M, Kohlberger C, Manna S, Stroj S, Freund J, Yuan X, Schneider C, Ježek M, Höfling S, Basso Basset F, Huber-Loyola T, Rastelli A, Trotta R. A source of entangled photons based on a cavity-enhanced and strain-tuned GaAs quantum dot. ELIGHT 2024; 4:13. [PMID: 39070906 PMCID: PMC11269457 DOI: 10.1186/s43593-024-00072-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/10/2024] [Accepted: 06/17/2024] [Indexed: 07/30/2024]
Abstract
A quantum-light source that delivers photons with a high brightness and a high degree of entanglement is fundamental for the development of efficient entanglement-based quantum-key distribution systems. Among all possible candidates, epitaxial quantum dots are currently emerging as one of the brightest sources of highly entangled photons. However, the optimization of both brightness and entanglement currently requires different technologies that are difficult to combine in a scalable manner. In this work, we overcome this challenge by developing a novel device consisting of a quantum dot embedded in a circular Bragg resonator, in turn, integrated onto a micromachined piezoelectric actuator. The resonator engineers the light-matter interaction to empower extraction efficiencies up to 0.69(4). Simultaneously, the actuator manipulates strain fields that tune the quantum dot for the generation of entangled photons with corrected fidelities to a maximally entangled state up to 0.96(1). This hybrid technology has the potential to overcome the limitations of the key rates that plague QD-based entangled sources for entanglement-based quantum key distribution and entanglement-based quantum networks. Supplementary Information The online version contains supplementary material available at 10.1186/s43593-024-00072-8.
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Affiliation(s)
- Michele B. Rota
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Tobias M. Krieger
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
| | - Quirin Buchinger
- Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Mattia Beccaceci
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Julia Neuwirth
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Hêlio Huet
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Nikola Horová
- Department of Optics, Faculty of Science, Palacký University, 17. Listopadu 1192/12, 77900 Olomouc, Czech Republic
| | - Gabriele Lovicu
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Giuseppe Ronco
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Saimon F. Covre da Silva
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
- Present Address: Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-859 Campinas, Brazil
| | - Giorgio Pettinari
- Institute for Photonics and Nanotechnologies, National Research Council, Via del Fosso del Cavaliere, 100, 00133 Rome, Italy
| | | | - Christoph Kohlberger
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
| | - Santanu Manna
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
| | - Sandra Stroj
- Research Center for Microtechnology, Vorarlberg University of Applied Sciences, Campus V, Hochschulstrasse 1, 6850 Dornbirn, Austria
| | - Julia Freund
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
| | - Xueyong Yuan
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
- Present Address: School of Physics, Southeast University, Nanjing, 211189 China
| | - Christian Schneider
- Institut für Physik, Fakultät V, Carl von Ossietzky, Universität Oldenburg, 26129 Oldenburg, Germany
| | - Miroslav Ježek
- Department of Optics, Faculty of Science, Palacký University, 17. Listopadu 1192/12, 77900 Olomouc, Czech Republic
| | - Sven Höfling
- Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Francesco Basso Basset
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Tobias Huber-Loyola
- Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Armando Rastelli
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenberger Strasse 69, 4040 Linz, Austria
| | - Rinaldo Trotta
- Dipartimento di Fisica, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
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2
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Dyte HE, Gillard G, Manna S, Covre da Silva SF, Rastelli A, Chekhovich EA. Is Wave Function Collapse Necessary? Explaining Quantum Nondemolition Measurement of a Spin Qubit within Linear Evolution. PHYSICAL REVIEW LETTERS 2024; 132:160804. [PMID: 38701456 DOI: 10.1103/physrevlett.132.160804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 01/28/2024] [Accepted: 03/14/2024] [Indexed: 05/05/2024]
Abstract
The measurement problem dates back to the dawn of quantum mechanics. Here, we measure a quantum dot electron spin qubit through off-resonant coupling with a highly redundant ancilla, consisting of thousands of nuclear spins. Large redundancy allows for single-shot measurement with high fidelity ≈99.85%. Repeated measurements enable heralded initialization of the qubit and backaction-free detection of electron spin quantum jumps, attributed to burstlike fluctuations in a thermally populated phonon bath. Based on these results we argue that the measurement, linking quantum states to classical observables, can be made without any "wave function collapse" in agreement with the Quantum Darwinism concept.
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Affiliation(s)
- Harry E Dyte
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
| | - George Gillard
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
| | - Santanu Manna
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria
| | - Saimon F Covre da Silva
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria
| | - Armando Rastelli
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria
| | - Evgeny A Chekhovich
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
- Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
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3
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Iyer PP, Prescott S, Addamane S, Jung H, Renteria E, Henshaw J, Mounce A, Luk TS, Mitrofanov O, Brener I. Control of Quantized Spontaneous Emission from Single GaAs Quantum Dots Embedded in Huygens' Metasurfaces. NANO LETTERS 2024. [PMID: 38620181 DOI: 10.1021/acs.nanolett.3c04846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Advancements in photonic quantum information systems (QIS) have driven the development of high-brightness, on-demand, and indistinguishable semiconductor epitaxial quantum dots (QDs) as single photon sources. Strain-free, monodisperse, and spatially sparse local-droplet-etched (LDE) QDs have recently been demonstrated as a superior alternative to traditional Stranski-Krastanov QDs. However, integration of LDE QDs into nanophotonic architectures with the ability to scale to many interacting QDs is yet to be demonstrated. We present a potential solution by embedding isolated LDE GaAs QDs within an Al0.4Ga0.6As Huygens' metasurface with spectrally overlapping fundamental electric and magnetic dipolar resonances. We demonstrate for the first time a position- and size-independent, 1 order of magnitude increase in the collection efficiency and emission lifetime control for single-photon emission from LDE QDs embedded within the Huygens' metasurfaces. Our results represent a significant step toward leveraging the advantages of LDE QDs within nanophotonic architectures to meet the scalability demands of photonic QIS.
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Affiliation(s)
- Prasad P Iyer
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Samuel Prescott
- University College London, Electronic and Electrical Engineering, London WC1E 7JE, U.K
| | - Sadhvikas Addamane
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Hyunseung Jung
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Emma Renteria
- Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87185, United States
| | - Jacob Henshaw
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Andrew Mounce
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Ting S Luk
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Oleg Mitrofanov
- University College London, Electronic and Electrical Engineering, London WC1E 7JE, U.K
| | - Igal Brener
- Center for Integrated Nanotechnologies, Sandia National Lab, Albuquerque, New Mexico 87185, United States
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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4
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Phillips CL, Brash AJ, Godsland M, Martin NJ, Foster A, Tomlinson A, Dost R, Babazadeh N, Sala EM, Wilson L, Heffernan J, Skolnick MS, Fox AM. Purcell-enhanced single photons at telecom wavelengths from a quantum dot in a photonic crystal cavity. Sci Rep 2024; 14:4450. [PMID: 38396018 PMCID: PMC11310300 DOI: 10.1038/s41598-024-55024-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
Quantum dots are promising candidates for telecom single photon sources due to their tunable emission across the different low-loss telecommunications bands, making them compatible with existing fiber networks. Their suitability for integration into photonic structures allows for enhanced brightness through the Purcell effect, supporting efficient quantum communication technologies. Our work focuses on InAs/InP QDs created via droplet epitaxy MOVPE to operate within the telecoms C-band. We observe a short radiative lifetime of 340 ps, arising from a Purcell factor of 5, owing to integration of the QD within a low-mode-volume photonic crystal cavity. Through in-situ control of the sample temperature, we show both temperature tuning of the QD's emission wavelength and a preserved single photon emission purity at temperatures up to 25K. These findings suggest the viability of QD-based, cryogen-free C-band single photon sources, supporting applicability in quantum communication technologies.
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Affiliation(s)
| | - Alistair J Brash
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Max Godsland
- EPSRC National Epitaxy Facility, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Nicholas J Martin
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Andrew Foster
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Anna Tomlinson
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - René Dost
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Nasser Babazadeh
- EPSRC National Epitaxy Facility, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Elisa M Sala
- EPSRC National Epitaxy Facility, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Luke Wilson
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Jon Heffernan
- EPSRC National Epitaxy Facility, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK
| | - Maurice S Skolnick
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - A Mark Fox
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
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5
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Liu RZ, Qiao YK, Lachman L, Ge ZX, Chung TH, Zhao JY, Li H, You L, Filip R, Huo YH. Experimental Quantum Non-Gaussian Coincidences of Entangled Photons. PHYSICAL REVIEW LETTERS 2024; 132:083601. [PMID: 38457704 DOI: 10.1103/physrevlett.132.083601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 01/24/2024] [Indexed: 03/10/2024]
Abstract
Quantum non-Gaussianity, a more potent and highly useful form of nonclassicality, excludes all convex mixtures of Gaussian states and Gaussian parametric processes generating them. Here, for the first time, we conclusively test quantum non-Gaussian coincidences of entangled photon pairs with the Clauser-Horne-Shimony-Holt-Bell factor S=2.328±0.004 from a single quantum dot with a depth up to 0.94±0.02 dB. Such deterministically generated photon pairs fundamentally overcome parametric processes by reducing crucial multiphoton errors. For the quantum non-Gaussian depth of the unheralded (heralded) single-photon state, we achieve the value of 8.08±0.05 dB (19.06±0.29 dB). Our Letter experimentally certifies the exclusive quantum non-Gaussianity properties highly relevant for optical sensing, communication, and computation.
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Affiliation(s)
- Run-Ze Liu
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Yu-Kun Qiao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Lukáš Lachman
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - Zhen-Xuan Ge
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Tung-Hsun Chung
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jun-Yi Zhao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
| | - Hao Li
- Shanghai Key Laboratory of Superconductor Integrated Circuit Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Lixing You
- Shanghai Key Laboratory of Superconductor Integrated Circuit Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Radim Filip
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - Yong-Heng Huo
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
- Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
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6
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Huang X, Horder J, Wong WW, Wang N, Bian Y, Yamamura K, Aharonovich I, Jagadish C, Tan HH. Scalable Bright and Pure Single Photon Sources by Droplet Epitaxy on InP Nanowire Arrays. ACS NANO 2024. [PMID: 38315082 DOI: 10.1021/acsnano.3c11071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
High-quality quantum light sources are crucial components for the implementation of practical and reliable quantum technologies. The persistent challenge, however, is the lack of scalable and deterministic single photon sources that can be synthesized reproducibly. Here, we present a combination of droplet epitaxy with selective area epitaxy to realize the deterministic growth of single quantum dots in nanowire arrays. By optimization of the single quantum dot growth and the nanowire cavity design, single emissions are effectively coupled with the dominant mode of the nanowires to realize Purcell enhancement. The resonance-enhanced quantum emitter system boasts a brightness of millions of counts per second with nanowatt excitation power, a short radiation lifetime of 350 ± 5 ps, and a high single-photon purity with g(2)(0) value of 0.05 with continuous wave above-band excitation. Finite-difference time-domain (FDTD) simulation results show that the emissions of single quantum dots are coupled into the TM01 mode of the nanowires, giving a Purcell factor ≈ 3. Our technology can be used for creating on-chip scalable single photon sources for future quantum technology applications including quantum networks, quantum computation, and quantum imaging.
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Affiliation(s)
- Xiaoying Huang
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Jake Horder
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Wei Wen Wong
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Naiyin Wang
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Yue Bian
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Karin Yamamura
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Igor Aharonovich
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Chennupati Jagadish
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
| | - Hark Hoe Tan
- Department of Electronic Materials Engineering, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
- Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
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7
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Cui Y, Wang J, Li Y, Wu Y, Been E, Zhang Z, Zhou J, Zhang W, Hwang HY, Sinclair R, Cui Y. Twisted epitaxy of gold nanodisks grown between twisted substrate layers of molybdenum disulfide. Science 2024; 383:212-219. [PMID: 38207038 DOI: 10.1126/science.adk5947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/27/2023] [Indexed: 01/13/2024]
Abstract
We expand the concept of epitaxy to a regime of "twisted epitaxy" with the epilayer crystal orientation between two substrates influenced by their relative orientation. We annealed nanometer-thick gold (Au) nanoparticles between two substrates of exfoliated hexagonal molybdenum disulfide (MoS2) with varying orientation of their basal planes with a mutual twist angle ranging from 0° to 60°. Transmission electron microscopy studies show that Au aligns midway between the top and bottom MoS2 when the twist angle of the bilayer is small (<~7°). For larger twist angles, Au has only a small misorientation with the bottom MoS2 that varies approximately sinusoidally with twist angle of the bilayer MoS2. Four-dimensional scanning transmission electron microscopy analysis further reveals a periodic strain variation (<|±0.5%|) in the Au nanodisks associated with the twisted epitaxy, consistent with the Moiré registry of the two MoS2 twisted layers.
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Affiliation(s)
- Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jingyang Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94305, USA
| | - Yanbin Li
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yecun Wu
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Emily Been
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Zewen Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Jiawei Zhou
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Wenbo Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Harold Y Hwang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Robert Sinclair
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Energy Science and Engineering, Stanford University, Stanford, CA 94305, USA
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8
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Yu Y, Liu S, Lee CM, Michler P, Reitzenstein S, Srinivasan K, Waks E, Liu J. Telecom-band quantum dot technologies for long-distance quantum networks. NATURE NANOTECHNOLOGY 2023; 18:1389-1400. [PMID: 38049595 DOI: 10.1038/s41565-023-01528-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 09/15/2023] [Indexed: 12/06/2023]
Abstract
A future quantum internet is expected to generate, distribute, store and process quantum bits (qubits) over the world by linking different quantum nodes via quantum states of light. To facilitate long-haul operations, quantum repeaters must operate at telecom wavelengths to take advantage of both the low-loss optical fibre network and the established technologies of modern optical communications. Semiconductor quantum dots have thus far shown exceptional performance as key elements for quantum repeaters, such as quantum light sources and spin-photon interfaces, but only in the near-infrared regime. Therefore, the development of high-performance telecom-band quantum dot devices is highly desirable for a future solid-state quantum internet based on fibre networks. In this Review, we present the physics and technological developments towards epitaxial quantum dot devices emitting in the telecom O- and C-bands for quantum networks, considering both advanced epitaxial growth for direct telecom emission and quantum frequency conversion for telecom-band down-conversion of near-infrared quantum dot devices. We also discuss the challenges and opportunities for future realization of telecom quantum dot devices with improved performance and expanded functionality through hybrid integration.
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Affiliation(s)
- Ying Yu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, School of Physics, Sun Yat-sen University, Guangzhou, China
| | - Shunfa Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, School of Physics, Sun Yat-sen University, Guangzhou, China
| | - Chang-Min Lee
- Department of Electrical and Computer Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA
| | - Peter Michler
- Institut für Halbleiteroptik und Funktionelle Grenzflächen (IHFG), Center for Integrated Quantum Science and Technology (IQST) and SCoPE, University of Stuttgart, Stuttgart, Germany
| | - Stephan Reitzenstein
- Institute of Solid State Physics, Technische Universität Berlin, Berlin, Germany
| | - Kartik Srinivasan
- Joint Quantum Institute, NIST/University of Maryland, College Park, MD, USA
- Microsystems and Nanotechnology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Edo Waks
- Department of Electrical and Computer Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, MD, USA
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, School of Physics, Sun Yat-sen University, Guangzhou, China.
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9
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Benter S, Jönsson A, Johansson J, Zhu L, Golias E, Wernersson LE, Mikkelsen A. Geometric control of diffusing elements on InAs semiconductor surfaces via metal contacts. Nat Commun 2023; 14:4541. [PMID: 37500640 PMCID: PMC10374539 DOI: 10.1038/s41467-023-40157-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/11/2023] [Indexed: 07/29/2023] Open
Abstract
Local geometric control of basic synthesis parameters, such as elemental composition, is important for bottom-up synthesis and top-down device definition on-chip but remains a significant challenge. Here, we propose to use lithographically defined metal stacks for regulating the surface concentrations of freely diffusing synthesis elements on compound semiconductors. This is demonstrated by geometric control of Indium droplet formation on Indium Arsenide surfaces, an important consequence of incongruent evaporation. Lithographic defined Aluminium/Palladium metal patterns induce well-defined droplet-free zones during annealing up to 600 °C, while the metal patterns retain their lateral geometry. Compositional and structural analysis is performed, as well as theoretical modelling. The Pd acts as a sink for free In atoms, lowering their surface concentration locally and inhibiting droplet formation. Al acts as a diffusion barrier altering Pd's efficiency. The behaviour depends only on a few basic assumptions and should be applicable to lithography-epitaxial manufacturing processes of compound semiconductors in general.
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Affiliation(s)
- Sandra Benter
- Department of Physics, Lund University, Box 118, Lund, 22100, Sweden.
- NanoLund Center for Nanoscience, Lund University, Box 118, Lund, 22100, Sweden.
| | - Adam Jönsson
- NanoLund Center for Nanoscience, Lund University, Box 118, Lund, 22100, Sweden
- Department of Electrical and Information Technology, LTH, Box 118, Lund, 22100, Sweden
| | - Jonas Johansson
- Department of Physics, Lund University, Box 118, Lund, 22100, Sweden
- NanoLund Center for Nanoscience, Lund University, Box 118, Lund, 22100, Sweden
| | - Lin Zhu
- MAX IV Laboratory, Lund University, Box 118, Lund, 22100, Sweden
| | - Evangelos Golias
- MAX IV Laboratory, Lund University, Box 118, Lund, 22100, Sweden
| | - Lars-Erik Wernersson
- NanoLund Center for Nanoscience, Lund University, Box 118, Lund, 22100, Sweden
- Department of Electrical and Information Technology, LTH, Box 118, Lund, 22100, Sweden
| | - Anders Mikkelsen
- Department of Physics, Lund University, Box 118, Lund, 22100, Sweden
- NanoLund Center for Nanoscience, Lund University, Box 118, Lund, 22100, Sweden
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10
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Jiang GQ, Zhang QH, Zhao JY, Qiao YK, Ge ZX, Liu RZ, Chung TH, Lu CY, Huo YH. Comprehensive measurement of the near-infrared refractive index of GaAs at cryogenic temperatures. OPTICS LETTERS 2023; 48:3507-3510. [PMID: 37390167 DOI: 10.1364/ol.491357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/27/2023] [Indexed: 07/02/2023]
Abstract
The refractive index is a critical parameter in optical and photonic device design. However, due to the lack of available data, precise designs of devices working in low temperatures are still frequently limited. In this work, we have built a homemade spectroscopic ellipsometer (SE) and measured the refractive index of GaAs at a matrix of temperatures (4 K < T < 295 K) and photon wavelengths (700 nm < λ < 1000 nm) with a system error of ∼0.04. We verified the credibility of the SE results by comparing them with afore-reported data at room temperature and with higher precision values measured by vertical GaAs cavity at cryogenic temperatures. This work makes up for the lack of the near-infrared refractive index of GaAs at cryogenic temperatures and provides accurate reference data for semiconductor device design and fabrication.
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11
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Di Liberto G, Tosoni S. Band Edges Engineering of 2D/2D Heterostructures: The C 3 N 4 /Phosphorene Interface. Chemphyschem 2023; 24:e202200791. [PMID: 36399544 DOI: 10.1002/cphc.202200791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/14/2022] [Indexed: 11/19/2022]
Abstract
We investigate the interface between carbon nitride (C3 N4 ) and phosphorene nanosheets (P-ene) by means of Density Functional Theory (DFT) calculations. C3 N4 /P-ene composites have been recently obtained experimentally showing excellent photoactivity. Our results indicate that the formation of the interface is a favorable process driven by Van der Waals forces. The thickness of P-ene nanosheets determines the band edges offsets and the charge carriers' separation. The system is predicted to pass from a nearly type-II to a type-I junction when the thickness of P-ene increases, and the conduction band offset is particularly sensitive. Last, we apply the Transfer Matrix Method to estimate the efficiency for charge carriers' migration as a function of the P-ene thickness.
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Affiliation(s)
- Giovanni Di Liberto
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy
| | - Sergio Tosoni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, 20125, Milano, Italy
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12
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Lehner BU, Seidelmann T, Undeutsch G, Schimpf C, Manna S, Gawełczyk M, Covre da Silva SF, Yuan X, Stroj S, Reiter DE, Axt VM, Rastelli A. Beyond the Four-Level Model: Dark and Hot States in Quantum Dots Degrade Photonic Entanglement. NANO LETTERS 2023; 23:1409-1415. [PMID: 36745448 PMCID: PMC9951244 DOI: 10.1021/acs.nanolett.2c04734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Entangled photon pairs are essential for a multitude of quantum photonic applications. To date, the best performing solid-state quantum emitters of entangled photons are semiconductor quantum dots operated around liquid-helium temperatures. To favor the widespread deployment of these sources, it is important to explore and understand their behavior at temperatures accessible with compact Stirling coolers. Here we study the polarization entanglement among photon pairs from the biexciton-exciton cascade in GaAs quantum dots at temperatures up to ∼65 K. We observe entanglement degradation accompanied by changes in decay dynamics, which we ascribe to thermal population and depopulation of hot and dark states in addition to the four levels relevant for photon pair generation. Detailed calculations considering the presence and characteristics of the additional states and phonon-assisted transitions support the interpretation. We expect these results to guide the optimization of quantum dots as sources of highly entangled photons at elevated temperatures.
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Affiliation(s)
- Barbara Ursula Lehner
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria
- Secure
and Correct Systems Lab, Linz Institute
of Technology, 4040Linz, Austria
| | - Tim Seidelmann
- Theoretische
Physik III, Universität Bayreuth, 95440Bayreuth, Germany
| | - Gabriel Undeutsch
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria
| | - Christian Schimpf
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria
| | - Santanu Manna
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria
| | - Michał Gawełczyk
- Institute
of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
| | | | - Xueyong Yuan
- School
of Physics, Southeast University, Nanjing211189, China
| | - Sandra Stroj
- Forschungszentrum
Mikrotechnik, FH Vorarlberg, 6850Dornbirn, Austria
| | - Doris E. Reiter
- Condensed
Matter Theory, TU Dortmund, 44221Dortmund, Germany
| | | | - Armando Rastelli
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria
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13
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Feddersen S, Zolatanosha V, Alshaikh A, Reuter D, Heyn C. Modeling of Masked Droplet Deposition for Site-Controlled Ga Droplets. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:466. [PMID: 36770427 PMCID: PMC9920042 DOI: 10.3390/nano13030466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/11/2023] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Site-controlled Ga droplets on AlGaAs substrates are fabricated using area-selective deposition of Ga through apertures in a mask during molecular beam epitaxy (MBE). The Ga droplets can be crystallized into GaAs quantum dots using a crystallization step under As flux. In order to model the complex process, including the masked deposition of the droplets and a reduction of their number during a thermal annealing step, a multiscale kinetic Monte Carlo (mkMC) simulation of self-assembled Ga droplet formation on AlGaAs is expanded for area-selective deposition. The simulation has only two free model parameters: the activation energy for surface diffusion and the activation energy for thermal escape of adatoms from a droplet. Simulated droplet numbers within the opening of the aperture agree quantitatively with the experimental results down to the perfect site-control, with one droplet per aperture. However, the model parameters are different compared to those of the self-assembled droplet growth. We attribute this to the presence of the mask in close proximity to the surface, which modifies the local process temperature and the As background. This approach also explains the dependence of the model parameters on the size of the aperture.
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Affiliation(s)
- Stefan Feddersen
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Viktoryia Zolatanosha
- Department of Physics, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
| | - Ahmed Alshaikh
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Dirk Reuter
- Department of Physics, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
| | - Christian Heyn
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany
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14
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Fricker D, Atkinson P, Jin X, Lepsa M, Zeng Z, Kovács A, Kibkalo L, Dunin-Borkowski RE, Kardynał BE. Effect of surface gallium termination on the formation and emission energy of an InGaAs wetting layer during the growth of InGaAs quantum dots by droplet epitaxy. NANOTECHNOLOGY 2023; 34:145601. [PMID: 36595322 DOI: 10.1088/1361-6528/acabd1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 12/14/2022] [Indexed: 06/17/2023]
Abstract
Self-assembled quantum dots (QDs) based on III-V semiconductors have excellent properties for applications in quantum optics. However, the presence of a 2D wetting layer (WL) which forms during the Stranski-Krastanov growth of QDs can limit their performance. Here, we investigate WL formation during QD growth by the droplet epitaxy technique. We use a combination of photoluminescence excitation spectroscopy, lifetime measurements, and transmission electron microscopy to identify the presence of an InGaAs WL in these droplet epitaxy QDs, even in the absence of distinguishable WL luminescence. We observe that increasing the amount of Ga deposited on a GaAs (100) surface prior to the growth of InGaAs QDs leads to a significant reduction in the emission wavelength of the WL to the point where it can no longer be distinguished from the GaAs acceptor peak emission in photoluminescence measurements. However increasing the amount of Ga deposited does not suppress the formation of a WL under the growth conditions used here.
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Affiliation(s)
- D Fricker
- Peter Grünberg Institute 9, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, D-52074 Aachen, Germany
| | - P Atkinson
- Institut des Nano Sciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - X Jin
- Peter Grünberg Institute 9, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, D-52074 Aachen, Germany
| | - M Lepsa
- Peter Grünberg Institute 9, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Peter Grünberg Institute 10, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Z Zeng
- Peter Grünberg Institute 9, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, D-52074 Aachen, Germany
| | - A Kovács
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute 5, Forschungszentrum Jülich, D-52428 Jülich, Germany
| | - L Kibkalo
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute 5, Forschungszentrum Jülich, D-52428 Jülich, Germany
| | - R E Dunin-Borkowski
- Department of Physics, RWTH Aachen University, D-52074 Aachen, Germany
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute 5, Forschungszentrum Jülich, D-52428 Jülich, Germany
| | - B E Kardynał
- Peter Grünberg Institute 9, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Department of Physics, RWTH Aachen University, D-52074 Aachen, Germany
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15
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Park S, Kim M, Kim I, Taylor RA, Song J, Kyhm K. Elliptical Polarization of Localized States in an Anisotropic Single GaAs Quantum Ring. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:184. [PMID: 36616094 PMCID: PMC9823924 DOI: 10.3390/nano13010184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/23/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
Localized states in an anisotropic single GaAs quantum ring were investigated in terms of polarization dependence of micro-photoluminescence spectrum at 5K. Given four Stokes parameters measured with a pair of linear polarizers and waveplates, the elliptical polarization states of two different vertical confinement states (k=1 and k=2) were compared with phase, rotation, and ellipticity angles. While the polarized emission intensity of the k=2 states becomes enhanced along [1,1,0] compared to that along [1,1¯,0], the polarization asymmetry of the k=1 states shows the opposite result. We conclude the polarization state is determined by the shape of the lateral wavefunctions. In the k=2 state, crescent-like wavefunctions are strongly localized, but the k=1 state consists of two crescent-like wavefunctions, which are connected weakly through quantum tunneling.
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Affiliation(s)
- Seongho Park
- Department of Opto/Cogno-Mechatronics Engineering, Research Center for Dielectric Advanced Matter Physic (RCDAMP), Pusan National University, Busan 46241, Republic of Korea
| | - Minju Kim
- Smart Gym-Based Translational Research Center for Active Senior’s Healthcare, Pukyong National University, Busan 48516, Republic of Korea
| | - Inhong Kim
- Department of Opto/Cogno-Mechatronics Engineering, Research Center for Dielectric Advanced Matter Physic (RCDAMP), Pusan National University, Busan 46241, Republic of Korea
| | | | - Jindong Song
- Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Kwangseuk Kyhm
- Department of Opto/Cogno-Mechatronics Engineering, Research Center for Dielectric Advanced Matter Physic (RCDAMP), Pusan National University, Busan 46241, Republic of Korea
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16
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Zhao X, Wang T, Sheng B, Zheng X, Chen L, Liu H, He C, Xu J, Zhu R, Wang X. Cathodoluminescence Spectroscopy in Graded In xGa 1-xN. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3719. [PMID: 36364495 PMCID: PMC9658634 DOI: 10.3390/nano12213719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/05/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
InGaN materials are widely used in optoelectronic devices due to their excellent optical properties. Since the emission wavelength of the full-composition-graded InxGa1-xN films perfectly matches the solar spectrum, providing a full-spectrum response, this makes them suitable for the manufacturing of high-efficiency optoelectronic devices. It is extremely important to study the optical properties of materials, but there are very few studies of the luminescence of full-composition-graded InxGa1-xN ternary alloy. In this work, the optical properties of full-composition-graded InxGa1-xN films are studied by cathodoluminescence (CL). The CL spectra with multiple luminescence peaks in the range of 365-1000 nm were acquired in the cross-sectional and plan-view directions. The CL spectroscopy studies were carried out inside and outside of microplates formed under the indium droplets on the InGaN surface, which found that the intensity of the light emission peaks inside and outside of microplates differed significantly. Additionally, the paired defects structure is studied by using the spectroscopic method. A detailed CL spectroscopy study paves the way for the growth and device optimization of high-quality, full-composition-graded InxGa1-xN ternary alloy materials.
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Affiliation(s)
- Xiaofang Zhao
- School of Materials Science and Engineering, Tiangong University, Tianjin 300387, China
| | - Tao Wang
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Bowen Sheng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Xiantong Zheng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Li Chen
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Haihui Liu
- School of Materials Science and Engineering, Tiangong University, Tianjin 300387, China
| | - Chao He
- Beijing Goldenscope Technology Co., Ltd., Beijing 100190, China
| | - Jun Xu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Rui Zhu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Xinqiang Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China
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17
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Heyn C, Gräfenstein A, Pirard G, Ranasinghe L, Deneke K, Alshaikh A, Bester G, Hansen W. Dot-Size Dependent Excitons in Droplet-Etched Cone-Shell GaAs Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12172981. [PMID: 36080018 PMCID: PMC9457581 DOI: 10.3390/nano12172981] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 06/01/2023]
Abstract
Strain-free GaAs quantum dots (QDs) are fabricated by filling droplet-etched nanoholes in AlGaAs. Using a template of nominally identical nanoholes, the QD size is precisely controlled by the thickness of the GaAs filling layer. Atomic force microscopy indicates that the QDs have a cone-shell shape. From single-dot photoluminescence measurements, values of the exciton emission energy (1.58...1.82 eV), the exciton-biexciton splitting (1.8...2.5 meV), the exciton radiative lifetime of bright (0.37...0.58 ns) and dark (3.2...6.7 ns) states, the quantum efficiency (0.89...0.92), and the oscillator strength (11.2...17.1) are determined as a function of the dot size. The experimental data are interpreted by comparison with an atomistic model.
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Affiliation(s)
- Christian Heyn
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Andreas Gräfenstein
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Geoffrey Pirard
- Physical Chemistry and Physics Departments, University of Hamburg, HARBOR Build., Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Leonardo Ranasinghe
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Kristian Deneke
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Ahmed Alshaikh
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Gabriel Bester
- Physical Chemistry and Physics Departments, University of Hamburg, HARBOR Build., Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Wolfgang Hansen
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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18
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Das T, Di Liberto G, Pacchioni G. Quantum confinement in chalcogenides 2D nanostructures from first principles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:405301. [PMID: 35868296 DOI: 10.1088/1361-648x/ac838b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
We investigated the impact of quantum confinement on the band gap of chalcogenides 2D nanostructures by means of density functional theory. We studied six different systems: MoS2, WS2, SnS2, GaS, InSe, and HfS2and we simulated nanosheets of increasing thickness, ranging from ultrathin films to ∼10-13 nm thick slabs, a size where the properties converge to the bulk. In some cases, the convergence of the band gap with slab thickness is rather slow, and sizeable deviations from the bulk value are still present with few nm-thick sheets. The results of the simulations were compared with the available experimental data, finding a quantitative agreement. The impact of quantum confinement can be rationalized in terms of effective masses of electrons and holes and system's size. These results show the possibility of reliably describing quantum confinement effects on systems for which experimental data are not available.
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Affiliation(s)
- Tilak Das
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, Milano, 20125, Italy
| | - Giovanni Di Liberto
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, Milano, 20125, Italy
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 55, Milano, 20125, Italy
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19
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Zhai L, Nguyen GN, Spinnler C, Ritzmann J, Löbl MC, Wieck AD, Ludwig A, Javadi A, Warburton RJ. Quantum interference of identical photons from remote GaAs quantum dots. NATURE NANOTECHNOLOGY 2022; 17:829-833. [PMID: 35589820 DOI: 10.1038/s41565-022-01131-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/01/2022] [Indexed: 06/15/2023]
Abstract
Photonic quantum technology provides a viable route to quantum communication1,2, quantum simulation3 and quantum information processing4. Recent progress has seen the realization of boson sampling using 20 single photons3 and quantum key distribution over hundreds of kilometres2. Scaling the complexity requires architectures containing multiple photon sources, photon counters and a large number of indistinguishable single photons. Semiconductor quantum dots are bright and fast sources of coherent single photons5-9. For applications, a roadblock is the poor quantum coherence on interfering single photons created by independent quantum dots10,11. Here we demonstrate two-photon interference with near-unity visibility (93.0 ± 0.8)% using photons from two completely separate GaAs quantum dots. The experiment retains all the emission into the zero phonon line-only the weak phonon sideband is rejected; temporal post-selection is not employed. By exploiting quantum interference, we demonstrate a photonic controlled-not circuit and an entanglement with fidelity of (85.0 ± 1.0)% between photons of different origins. The two-photon interference visibility is high enough that the entanglement fidelity is well above the classical threshold. The high mutual coherence of the photons stems from high-quality materials, diode structure and relatively large quantum dot size. Our results establish a platform-GaAs quantum dots-for creating coherent single photons in a scalable way.
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Affiliation(s)
- Liang Zhai
- Department of Physics, University of Basel, Basel, Switzerland.
| | - Giang N Nguyen
- Department of Physics, University of Basel, Basel, Switzerland
| | | | - Julian Ritzmann
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Matthias C Löbl
- Department of Physics, University of Basel, Basel, Switzerland
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Alisa Javadi
- Department of Physics, University of Basel, Basel, Switzerland
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20
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Gajjela RSR, Sala EM, Heffernan J, Koenraad PM. Control of Morphology and Substrate Etching in InAs/InP Droplet Epitaxy Quantum Dots for Single and Entangled Photon Emitters. ACS APPLIED NANO MATERIALS 2022; 5:8070-8079. [PMID: 35783681 PMCID: PMC9237823 DOI: 10.1021/acsanm.2c01197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
We present a detailed atomic-resolution study of morphology and substrate etching mechanism in InAs/InP droplet epitaxy quantum dots (QDs) grown by metal-organic vapor phase epitaxy via cross-sectional scanning tunneling microscopy (X-STM). Two different etching processes are observed depending on the crystallization temperature: local drilling and long-range etching. In local drilling occurring at temperatures of ≤500 °C, the In droplet locally liquefies the InP underneath and the P atoms can easily diffuse out of the droplet to the edges. During crystallization, the As atoms diffuse into the droplet and crystallize at the solid-liquid interface, forming an InAs etch pit underneath the QD. In long-range etching, occurring at higher temperatures of >500 °C, the InP layer is destabilized and the In atoms from the surroundings migrate toward the droplet. The P atoms can easily escape from the surface into the vacuum, forming trenches around the QD. We show for the first time the formation of trenches and long-range etching in InAs/InP QDs with atomic resolution. Both etching processes can be suppressed by growing a thin layer of InGaAs prior to the droplet deposition. The QD composition is estimated by finite element modeling in combination with X-STM. The change in the morphology of QDs due to etching can strongly influence the fine structure splitting. Therefore, the current atomic-resolution study sheds light on the morphology and etching behavior as a function of crystallization temperature and provides a valuable insight into the formation of InAs/InP droplet epitaxy QDs which have potential applications in quantum information technologies.
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Affiliation(s)
- Raja Sekhar Reddy Gajjela
- Department
of Applied Physics, Eindhoven University
of Technology, Eindhoven 5612 AZ, The Netherlands
| | - Elisa Maddalena Sala
- EPSRC
National Epitaxy Facility, The University
of Sheffield, North Campus, Broad Lane, S3 7HQ Sheffield, United Kingdom
- Department
of Electronic and Electrical Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin Street, S1 3JD Sheffield, United Kingdom
| | - Jon Heffernan
- EPSRC
National Epitaxy Facility, The University
of Sheffield, North Campus, Broad Lane, S3 7HQ Sheffield, United Kingdom
- Department
of Electronic and Electrical Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin Street, S1 3JD Sheffield, United Kingdom
| | - Paul M. Koenraad
- Department
of Applied Physics, Eindhoven University
of Technology, Eindhoven 5612 AZ, The Netherlands
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21
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Ru F, Xia J, Li X, Liu P, Qiao P, Li Y, Cao J, Tian L, Zhang W, Meng XM. Epitaxial growth of structure-tunable ZnO/ZnS core/shell nanowire arrays using HfO 2 as the buffer layer. NANOSCALE 2022; 14:7579-7588. [PMID: 35506868 DOI: 10.1039/d2nr01560a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Synthesis of high-quality ZnO/ZnS heterostructures with tunable phase and controlled structures is in high demand due to their adjustable band gap and efficient electron-hole pair separation. In this report, for the first time, remote heteroepitaxy of single-crystalline ZnO/ZnS core/shell nanowire arrays has been realized using amorphous HfO2 as the buffer layer. Zinc blende or wurtzite ZnS epilayer can be efficiently fabricated under the same thermal deposition condition by adjusting the buffer layer thickness, even among the same batch of products, respectively. Structural characterization reveals "(01-10)ZnOwz//(2-20)ZnSZB, [0001]ZnOWZ//[001]ZnSZB" and "(01-10)ZnOWZ//(01-10)ZnSWZ, [0002]ZnOWZ//[0002]ZnSWZ" epitaxial relationships between the core and the shell, respectively. The cathodoluminescence measurement demonstrates that the tuning of the optical properties can be accomplished by preparing a heterostructure with HfO2, in which a strong green emission increases at the expense of the quenching of UV emission. In addition, the core/shell heterostructure based Schottky diode exhibits an asymmetrical rectifying behavior and an outstanding photo-electronic switching-effect. We believe that the aforementioned results could provide fundamental insights for epitaxial growth of structure-tunable ZnO/ZnS heterostructures on the nanoscale. Furthermore, this promising route buffered by the high-k material can broaden the options for fabricating heterojunctions and promote their application in photoelectric nanodevices.
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Affiliation(s)
- Fan Ru
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Jing Xia
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Xuanze Li
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Pei Liu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Peiyu Qiao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Yuye Li
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Jianyu Cao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Lifeng Tian
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
| | - Wenjun Zhang
- Center of Super-Diamond and Advanced Films (COSADF) and Department of Materials Science and Engineering, City University of Hong Kong SAR, P.R.China
| | - Xiang-Min Meng
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
- Centre of Material Science and Optoelectronic Engineering, University of Chinese Academy of Science, Beijing, 10049, P. R. China
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22
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Gajjela RSR, van Venrooij NRS, da Cruz AR, Skiba-Szymanska J, Stevenson RM, Shields AJ, Pryor CE, Koenraad PM. Study of Size, Shape, and Etch pit formation in InAs/InP Droplet Epitaxy Quantum Dots. NANOTECHNOLOGY 2022; 33:305705. [PMID: 35395644 DOI: 10.1088/1361-6528/ac659e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
We investigated metal-organic vapor phase epitaxy grown droplet epitaxy (DE) and Stranski-Krastanov (SK) InAs/InP quantum dots (QDs) by cross-sectional scanning tunneling microscopy (X-STM). We present an atomic-scale comparison of structural characteristics of QDs grown by both growth methods proving that the DE yields more uniform and shape-symmetric QDs. Both DE and SKQDs are found to be truncated pyramid-shaped with a large and sharp top facet. We report the formation of localized etch pits for the first time in InAs/InP DEQDs with atomic resolution. We discuss the droplet etching mechanism in detail to understand the formation of etch pits underneath the DEQDs. A summary of the effect of etch pit size and position on fine structure splitting (FSS) is provided via thek·ptheory. Finite element (FE) simulations are performed to fit the experimental outward relaxation and lattice constant profiles of the cleaved QDs. The composition of QDs is estimated to be pure InAs obtained by combining both FE simulations and X-STM results. The preferential formation of {136} and {122} side facets was observed for the DEQDs. The formation of a DE wetting layer from As-P surface exchange is compared with the standard SKQDs wetting layer. The detailed structural characterization performed in this work provides valuable feedback for further growth optimization to obtain QDs with even lower FSS for applications in quantum technology.
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Affiliation(s)
- Raja S R Gajjela
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ, The Netherlands
| | - Niels R S van Venrooij
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ, The Netherlands
| | - Adonai R da Cruz
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ, The Netherlands
| | - Joanna Skiba-Szymanska
- Toshiba Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge CB4 0GZ, United Kingdom
| | - R Mark Stevenson
- Toshiba Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge CB4 0GZ, United Kingdom
| | - Andrew J Shields
- Toshiba Europe Limited, Cambridge Research Laboratory, 208 Science Park, Milton Road, Cambridge CB4 0GZ, United Kingdom
| | - Craig E Pryor
- Department of Physics and Astronomy, Optical Science and Technology Center, University of Iowa, Iowa City, Iowa IA-52242, United States of America
| | - Paul M Koenraad
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ, The Netherlands
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23
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Wafer-scale epitaxial modulation of quantum dot density. Nat Commun 2022; 13:1633. [PMID: 35347120 PMCID: PMC8960873 DOI: 10.1038/s41467-022-29116-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/23/2022] [Indexed: 11/08/2022] Open
Abstract
Precise control of the properties of semiconductor quantum dots (QDs) is vital for creating novel devices for quantum photonics and advanced opto-electronics. Suitable low QD-densities for single QD devices and experiments are challenging to control during epitaxy and are typically found only in limited regions of the wafer. Here, we demonstrate how conventional molecular beam epitaxy (MBE) can be used to modulate the density of optically active QDs in one- and two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients during layer-by-layer growth result in surface roughness modulations across the whole wafer. Growth on such templates strongly influences the QD nucleation probability. We obtain density modulations between 1 and 10 QDs/µm2 and periods ranging from several millimeters down to at least a few hundred microns. This method is universal and expected to be applicable to a wide variety of different semiconductor material systems. We apply the method to enable growth of ultra-low noise QDs across an entire 3-inch semiconductor wafer. Nucleation control of self-assembled quantum dots is challenging. Here, the authors employ conventional molecular beam epitaxy to achieve wafer-scale density modulation of high-quality quantum dots with tunable periodicity on unpatterned substrates.
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24
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Varo S, Juska G, Pelucchi E. An intuitive protocol for polarization-entanglement restoral of quantum dot photon sources with non-vanishing fine-structure splitting. Sci Rep 2022; 12:4723. [PMID: 35304526 PMCID: PMC8933574 DOI: 10.1038/s41598-022-08535-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
Generation of polarization-entangled photons from quantum dots via the biexciton-exciton recombination cascade is complicated by the presence of an energy splitting between the intermediate excitonic levels, which severely degrades the quality of the entangled photon source. In this paper we present a novel, conceptually simple and straightforward proposal for restoring the entanglement of said source by applying a cascade of time-dependent operations on the emitted photons. This is in striking contrast with the techniques usually employed, that act on the quantum emitter itself in order to remove the fine structure splitting at its root. The feasibility of the implementation with current technology is discussed, and the robustness of the proposed compensation scheme with respect to imperfections of the experimental apparatus is evaluated via a series of Monte Carlo simulations.
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Affiliation(s)
- Simone Varo
- Tyndall National Institute, University College Cork, Dyke Parade, Cork, Republic of Ireland.
| | - Gediminas Juska
- Tyndall National Institute, University College Cork, Dyke Parade, Cork, Republic of Ireland
| | - Emanuele Pelucchi
- Tyndall National Institute, University College Cork, Dyke Parade, Cork, Republic of Ireland
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25
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Sala EM, Godsland M, Na YI, Trapalis A, Heffernan J. Droplet epitaxy of InAs/InP quantum dots via MOVPE by using an InGaAs interlayer. NANOTECHNOLOGY 2021; 33:065601. [PMID: 34731846 DOI: 10.1088/1361-6528/ac3617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/03/2021] [Indexed: 06/13/2023]
Abstract
InAs quantum dots (QDs) are grown on an In0.53Ga0.47As interlayer and embedded in an InP(100) matrix. They are fabricated via droplet epitaxy (DE) in a metal organic vapor phase epitaxy (MOVPE) reactor. Formation of metallic indium droplets on the In0.53Ga0.47As lattice-matched layer and their crystallization into QDs is demonstrated for the first time in MOVPE. The presence of the In0.53Ga0.47As layer prevents the formation of an unintentional non-stoichiometric 2D layer underneath and around the QDs, via suppression of the As-P exchange. The In0.53Ga0.47As layer affects the surface diffusion leading to a modified droplet crystallization process, where unexpectedly the size of the resulting QDs is found to be inversely proportional to the indium supply. Bright single dot emission is detected via micro-photoluminescence at low temperature, ranging from 1440 to 1600 nm, covering the technologically relevant telecom C-band. Transmission electron microscopy investigations reveal buried quantum dots with truncated pyramid shape without defects or dislocations.
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Affiliation(s)
- Elisa M Sala
- EPSRC National Epitaxy Facility, The University of Sheffield, North Campus, Broad Lane, S3 7HQ Sheffield, United Kingdom
- Department of Electronic and Electrical Engineering, The University of Sheffield, North Campus, Broad Lane, S37HQ Sheffield, United Kingdom
| | - Max Godsland
- Department of Electronic and Electrical Engineering, The University of Sheffield, North Campus, Broad Lane, S37HQ Sheffield, United Kingdom
| | - Young In Na
- Department of Electronic and Electrical Engineering, The University of Sheffield, North Campus, Broad Lane, S37HQ Sheffield, United Kingdom
| | - Aristotelis Trapalis
- EPSRC National Epitaxy Facility, The University of Sheffield, North Campus, Broad Lane, S3 7HQ Sheffield, United Kingdom
- Department of Electronic and Electrical Engineering, The University of Sheffield, North Campus, Broad Lane, S37HQ Sheffield, United Kingdom
| | - Jon Heffernan
- EPSRC National Epitaxy Facility, The University of Sheffield, North Campus, Broad Lane, S3 7HQ Sheffield, United Kingdom
- Department of Electronic and Electrical Engineering, The University of Sheffield, North Campus, Broad Lane, S37HQ Sheffield, United Kingdom
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26
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Babin HG, Ritzmann J, Bart N, Schmidt M, Kruck T, Zhai L, Löbl MC, Nguyen GN, Spinnler C, Ranasinghe L, Warburton RJ, Heyn C, Wieck AD, Ludwig A. Charge Tunable GaAs Quantum Dots in a Photonic n-i-p Diode. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2703. [PMID: 34685139 PMCID: PMC8537184 DOI: 10.3390/nano11102703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/06/2021] [Accepted: 10/11/2021] [Indexed: 12/03/2022]
Abstract
In this submission, we discuss the growth of charge-controllable GaAs quantum dots embedded in an n-i-p diode structure, from the perspective of a molecular beam epitaxy grower. The QDs show no blinking and narrow linewidths. We show that the parameters used led to a bimodal growth mode of QDs resulting from low arsenic surface coverage. We identify one of the modes as that showing good properties found in previous work. As the morphology of the fabricated QDs does not hint at outstanding properties, we attribute the good performance of this sample to the low impurity levels in the matrix material and the ability of n- and p-doped contact regions to stabilize the charge state. We present the challenges met in characterizing the sample with ensemble photoluminescence spectroscopy caused by the photonic structure used. We show two straightforward methods to overcome this hurdle and gain insight into QD emission properties.
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Affiliation(s)
- Hans Georg Babin
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Julian Ritzmann
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Nikolai Bart
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Marcel Schmidt
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Timo Kruck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Liang Zhai
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland; (L.Z.); (M.C.L.); (G.N.N.); (C.S.); (R.J.W.)
| | - Matthias C. Löbl
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland; (L.Z.); (M.C.L.); (G.N.N.); (C.S.); (R.J.W.)
| | - Giang N. Nguyen
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland; (L.Z.); (M.C.L.); (G.N.N.); (C.S.); (R.J.W.)
| | - Clemens Spinnler
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland; (L.Z.); (M.C.L.); (G.N.N.); (C.S.); (R.J.W.)
| | - Leonardo Ranasinghe
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, DE-22761 Hamburg, Germany; (L.R.); (C.H.)
| | - Richard J. Warburton
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland; (L.Z.); (M.C.L.); (G.N.N.); (C.S.); (R.J.W.)
| | - Christian Heyn
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, DE-22761 Hamburg, Germany; (L.R.); (C.H.)
| | - Andreas D. Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany; (J.R.); (N.B.); (M.S.); (T.K.); (A.D.W.); (A.L.)
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27
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García de Arquer FP, Talapin DV, Klimov VI, Arakawa Y, Bayer M, Sargent EH. Semiconductor quantum dots: Technological progress and future challenges. Science 2021; 373:373/6555/eaaz8541. [PMID: 34353926 DOI: 10.1126/science.aaz8541] [Citation(s) in RCA: 337] [Impact Index Per Article: 112.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In quantum-confined semiconductor nanostructures, electrons exhibit distinctive behavior compared with that in bulk solids. This enables the design of materials with tunable chemical, physical, electrical, and optical properties. Zero-dimensional semiconductor quantum dots (QDs) offer strong light absorption and bright narrowband emission across the visible and infrared wavelengths and have been engineered to exhibit optical gain and lasing. These properties are of interest for imaging, solar energy harvesting, displays, and communications. Here, we offer an overview of advances in the synthesis and understanding of QD nanomaterials, with a focus on colloidal QDs, and discuss their prospects in technologies such as displays and lighting, lasers, sensing, electronics, solar energy conversion, photocatalysis, and quantum information.
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Affiliation(s)
- F Pelayo García de Arquer
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, ON M5S 1A4, Canada.,ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Barcelona 08860, Spain
| | - Dmitri V Talapin
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Victor I Klimov
- Chemistry Division, C-PCS, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | | - Manfred Bayer
- Technische Universitat Dortmund, 44221 Dortmund, Germany
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, 35 St. George Street, Toronto, ON M5S 1A4, Canada.
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28
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Heyn C. Design and operation of a portable micro-photoluminescence spectrometer for education on semiconductor quantum structures and graphene sheets. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053905. [PMID: 34243272 DOI: 10.1063/5.0050435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 05/01/2021] [Indexed: 06/13/2023]
Abstract
The design and operation of a portable micro-photoluminescence spectrometer for applications in education is described. Guidelines are a compact, robust, portable, and flexible design; operation without cryogenic media for sample cooling; and a limited budget. Targeted samples are semiconductor quantum structures emitting in a wavelength range of 600-1000 nm and graphene sheets. The portable spectrometer includes a reflected-light microscope with a motorized sample stage of 156 nm step size, a thermoelectric sample cooler allowing temperatures down to 196 K, a green and a blue laser for focused excitation, a monochromator with 0.18 nm spectral resolution, and a cooled camera as the image sensor. For demonstration of the capabilities of the spectrometer, measurements of the quantized energy levels of molecular beam epitaxy grown GaAs quantum dots (QDs) are shown. Here, different sample designs are used, the sample temperature as well as the laser excitation power and energy is varied, and the respective influence on the measurements is discussed. A clear QD shell structure with four states is shown for a sample, where approximately four QDs are directly excited by a focused laser. Limitations of the spectrometer for QD characterization mainly due to the waiver of cryogenic media for sample cooling are discussed. As a further example, which does not require sample cooling, local Raman spectroscopy of a graphene sheet is demonstrated where clear Raman signatures allow the identification of a single-layer thickness.
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Affiliation(s)
- Christian Heyn
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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29
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Balakirev SV, Chernenko NE, Eremenko MM, Ageev OA, Solodovnik MS. Independent Control Over Size and Surface Density of Droplet Epitaxial Nanostructures Using Ultra-Low Arsenic Fluxes. NANOMATERIALS 2021; 11:nano11051184. [PMID: 33946198 PMCID: PMC8146642 DOI: 10.3390/nano11051184] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/24/2021] [Accepted: 04/27/2021] [Indexed: 11/16/2022]
Abstract
Modern and future nanoelectronic and nanophotonic applications require precise control of the size, shape and density of III-V quantum dots in order to predefine the characteristics of devices based on them. In this paper, we propose a new approach to control the size of nanostructures formed by droplet epitaxy. We reveal that it is possible to reduce the droplet volume independently of the growth temperature and deposition amount by exposing droplets to ultra-low group-V flux. We carry out a thorough study of the effect of arsenic pressure on the droplet characteristics and demonstrate that indium droplets with a large initial size (>100 nm) and a low surface density (<108 cm-2) are able to shrink to dimensions appropriate for quantum dot applications. Small droplets are found to be unstable and difficult to control, while larger droplets are more resistive to arsenic flux and can be reduced to stable, small-sized nanostructures (~30 nm). We demonstrate the growth conditions under which droplets transform into dots, ring and holes and describe a mechanism of this transformation depending on the ultra-low arsenic flux. Thus, we observe phenomena which significantly expand the capabilities of droplet epitaxy.
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30
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Banerjee P, Roy C, Jiménez JJ, Morales FM, Bhattacharyya S. Atomically resolved 3D structural reconstruction of small quantum dots. NANOSCALE 2021; 13:7550-7557. [PMID: 33928976 DOI: 10.1039/d1nr00466b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Semiconducting quantum dots (QDs) have potential applications in light-emitting diodes, single-photon sources and quantum computing due to shape-dependent (opto) electronic properties. Atomic resolution 3D-structure determination is important in understanding growth kinetics and improving device performance. 3D-reconstruction of large QDs was reported using characterization techniques like atomic force microscopy, atom probe tomography and tilt series electron tomography, but, still, atomic resolution tomography of QDs, especially those sized below 10 nm, is a challenge. Inline-3D-holography is an emerging and promising technique to perform atomic resolution tomography at low electron doses. In the present study, atomically resolved 3D structures of QDs were reconstructed using inline-3D-holography, implemented on InN QDs (<10 nm) grown on a Si substrate. The residual amorphous glue distorts the exit surface geometry; hence an error correction method was proposed. This is the first experimental evidence of pre-pyramid shaped 3D structure of QDs sized below 10 nm that supports theoretical predictions.
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Affiliation(s)
- Pritam Banerjee
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Chiranjit Roy
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Juan Jesús Jiménez
- IMEYMAT: Institute of Research on Electron Microscopy and Materials, University of Cádiz, Spain and Department of Materials Science and Metallurgic Engineering, and Inorganic Chemistry, Faculty of Sciences, University of Cádiz, Puerto Real, 11510 Cádiz, Spain
| | - Francisco Miguel Morales
- IMEYMAT: Institute of Research on Electron Microscopy and Materials, University of Cádiz, Spain and Department of Materials Science and Metallurgic Engineering, and Inorganic Chemistry, Faculty of Sciences, University of Cádiz, Puerto Real, 11510 Cádiz, Spain
| | - Somnath Bhattacharyya
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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31
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Optical characteristics of type-II hexagonal-shaped GaSb quantum dots on GaAs synthesized using nanowire self-growth mechanism from Ga metal droplet. Sci Rep 2021; 11:7699. [PMID: 33833327 PMCID: PMC8032789 DOI: 10.1038/s41598-021-87321-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/25/2021] [Indexed: 11/16/2022] Open
Abstract
We report the growth mechanism and optical characteristics of type-II band-aligned GaSb quantum dots (QDs) grown on GaAs using a droplet epitaxy-driven nanowire formation mechanism with molecular beam epitaxy. Using transmission electron microscopy and scanning electron microscopy images, we confirmed that the QDs, which comprised zinc-blende crystal structures with hexagonal shapes, were successfully grown through the formation of a nanowire from a Ga droplet, with reduced strain between GaAs and GaSb. Photoluminescence (PL) peaks of GaSb capped by a GaAs layer were observed at 1.11 eV, 1.26 eV, and 1.47 eV, assigned to the QDs, a wetting-like layer (WLL), and bulk GaAs, respectively, at the measurement temperature of 14 K and excitation laser power of 30 mW. The integrated PL intensity of the QDs was significantly stronger than that of the WLL, which indicated well-grown GaSb QDs on GaAs and the generation of an interlayer exciton, as shown in the power- and temperature-dependent PL spectra, respectively. In addition, time-resolved PL data showed that the GaSb QD and GaAs layers formed a self-aligned type-II band alignment; the temperature-dependent PL data exhibited a high equivalent internal quantum efficiency of 15 ± 0.2%.
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32
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Schimpf C, Reindl M, Huber D, Lehner B, Covre Da Silva SF, Manna S, Vyvlecka M, Walther P, Rastelli A. Quantum cryptography with highly entangled photons from semiconductor quantum dots. SCIENCE ADVANCES 2021; 7:7/16/eabe8905. [PMID: 33853777 PMCID: PMC8046371 DOI: 10.1126/sciadv.abe8905] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 02/25/2021] [Indexed: 06/01/2023]
Abstract
Semiconductor quantum dots are capable of emitting polarization entangled photon pairs with ultralow multipair emission probability even at maximum brightness. Using a quantum dot source with a fidelity as high as 0.987(8), we implement here quantum key distribution with an average quantum bit error rate as low as 1.9% over a time span of 13 hours. For a proof of principle, the key generation is performed with the BBM92 protocol between two buildings, connected by a 350-m-long fiber, resulting in an average raw (secure) key rate of 135 bits/s (86 bits/s) for a pumping rate of 80 MHz, without resorting to time- or frequency-filtering techniques. Our work demonstrates the viability of quantum dots as light sources for entanglement-based quantum key distribution and quantum networks. By increasing the excitation rate and embedding the dots in state-of-the-art photonic structures, key generation rates in the gigabits per second range are in principle at reach.
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Affiliation(s)
- Christian Schimpf
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria.
| | - Marcus Reindl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
| | - Daniel Huber
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
| | - Barbara Lehner
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
| | - Saimon F Covre Da Silva
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
| | - Santanu Manna
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
| | - Michal Vyvlecka
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Vienna, Austria
- Doppler Laboratory for Photonic Quantum Computers, Faculty of Physics, University of Vienna, Vienna, Austria
| | - Philip Walther
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Vienna, Austria
- Doppler Laboratory for Photonic Quantum Computers, Faculty of Physics, University of Vienna, Vienna, Austria
| | - Armando Rastelli
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Linz, Austria
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Tuktamyshev A, Fedorov A, Bietti S, Vichi S, Tambone R, Tsukamoto S, Sanguinetti S. Nucleation of Ga droplets self-assembly on GaAs(111)A substrates. Sci Rep 2021; 11:6833. [PMID: 33767304 PMCID: PMC7994575 DOI: 10.1038/s41598-021-86339-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/15/2021] [Indexed: 11/10/2022] Open
Abstract
We investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around \documentclass[12pt]{minimal}
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\begin{document}$$350\,^{\circ }\hbox {C}$$\end{document}350∘C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.
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Affiliation(s)
- Artur Tuktamyshev
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy. .,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy.
| | - Alexey Fedorov
- CNR Istituto di Fotonica e Nanotecnologie, Piazza Leonardo da Vinci 32, 20133, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Sergio Bietti
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Stefano Vichi
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Riccardo Tambone
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Shiro Tsukamoto
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Stefano Sanguinetti
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
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Li X. The structural symmetry of nanoholes upon droplet epitaxy. NANOTECHNOLOGY 2021; 32:225602. [PMID: 33631728 DOI: 10.1088/1361-6528/abe9e5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Nanoholes obtained by droplet epitaxy has been intensively investigated as an important material platform for the fabrication of nanodevices due to their unique topology. However, the final fabricated nanoholes are very difficult to achieve a highly symmetric circular structure, and usually have two or four gaps in the sidewall of the holes. Here we have presented a developed model to inquire into the reasons for the formation of the gaps at the periphery of nanoholes and discuss how to improve the structural symmetry of the nanoholes. It is found that the anisotropic interface diffusion of As atoms decomposed by substrate can result in the formation of the gaps. In order to improve the symmetry of final nanostructures, we can minimize the interval time between deposition of Ga droplets and open operation of As flux, and set up a multistep growth procedure by changing the intensity of As flux or growth temperature.
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Affiliation(s)
- Xinlei Li
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People's Republic of China
- Guangdong Provincial Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People's Republic of China
- Guangzhou Key Laboratory of Spectral Analysis and Functional Probes, College of Biophotonics, South China Normal University, Guangzhou 510631, People's Republic of China
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35
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Heyn C, Feddersen S. Modeling of Al and Ga Droplet Nucleation during Droplet Epitaxy or Droplet Etching. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:468. [PMID: 33673053 PMCID: PMC7917698 DOI: 10.3390/nano11020468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/27/2021] [Accepted: 02/08/2021] [Indexed: 02/01/2023]
Abstract
The temperature dependent density of Al and Ga droplets deposited on AlGaAs with molecular beam epitaxy is studied theoretically. Such droplets are important for applications in quantum information technology and can be functionalized e.g., by droplet epitaxy or droplet etching for the self-assembled generation of quantum emitters. After an estimation based on a scaling analysis, the droplet densities are simulated using first a mean-field rate model and second a kinetic Monte Carlo (KMC) simulation basing on an atomistic representation of the mobile adatoms. The modeling of droplet nucleation with a very high surface activity of the adatoms and ultra-low droplet densities down to 5 × 106 cm-2 is highly demanding in particular for the KMC simulation. Both models consider two material related model parameters, the energy barrier ES for surface diffusion of free adatoms and the energy barrier EE for escape of atoms from droplets. The rate model quantitatively reproduces the droplet densities with ES = 0.19 eV, EE = 1.71 eV for Al droplets and ES = 0.115 eV for Ga droplets. For Ga, the values of EE are temperature dependent indicating the relevance of additional processes. Interestingly, the critical nucleus size depends on deposition time, which conflicts with the assumptions of the scaling model. Using a multiscale KMC algorithm to substantially shorten the computation times, Al droplets up to 460 °C on a 7500 × 7500 simulation field and Ga droplets up to 550 °C are simulated. The results show a very good agreement with the experiments using ES = 0.19 eV, EE = 1.44 eV for Al, and ES = 0.115 eV, EE = 1.24 eV (T≤ 300 °C) or EE = 1.24 + 0.06 (T[°C] - 300)/100 eV (T>300 °C) for Ga. The deviating EE is attributed to a re-nucleation effect that is not considered in the mean-field assumption of the rate model.
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Affiliation(s)
- Christian Heyn
- Center for Hybrid Nanostructures (CHyN), University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany;
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36
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Abbarchi M, Mano T, Kuroda T, Ohtake A, Sakoda K. Polarization Anisotropies in Strain-Free, Asymmetric, and Symmetric Quantum Dots Grown by Droplet Epitaxy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:443. [PMID: 33578657 PMCID: PMC7916409 DOI: 10.3390/nano11020443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 11/17/2022]
Abstract
We provide an extensive and systematic investigation of exciton dynamics in droplet epitaxial quantum dots comparing the cases of (311)A, (001), and (111)A surfaces. Despite a similar s-shell exciton structure common to the three cases, the absence of a wetting layer for (311)A and (111)A samples leads to a larger carrier confinement compared to (001), where a wetting layer is present. This leads to a more pronounced dependence of the binding energies of s-shell excitons on the quantum dot size and to the strong anti-binding character of the positive-charged exciton for smaller quantum dots. In-plane geometrical anisotropies of (311)A and (001) quantum dots lead to a large electron-hole fine interaction (fine structure splitting (FSS) ∼100 μeV), whereas for the three-fold symmetric (111)A counterpart, this figure of merit is reduced by about one order of magnitude. In all these cases, we do not observe any size dependence of the fine structure splitting. Heavy-hole/light-hole mixing is present in all the studied cases, leading to a broad spread of linear polarization anisotropy (from 0 up to about 50%) irrespective of surface orientation (symmetry of the confinement), fine structure splitting, and nanostructure size. These results are important for the further development of ideal single and entangled photon sources based on semiconductor quantum dots.
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Affiliation(s)
- Marco Abbarchi
- Aix Marseille Univ, Université de Toulon, CNRS, IM2NP Marseille, France
| | - Takaaki Mano
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Takashi Kuroda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Akihiro Ohtake
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
| | - Kazuaki Sakoda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (A.O.); (K.S.)
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37
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Optical Properties of Site-Selectively Grown InAs/InP Quantum Dots with Predefined Positioning by Block Copolymer Lithography. MATERIALS 2021; 14:ma14020391. [PMID: 33466881 PMCID: PMC7830905 DOI: 10.3390/ma14020391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/18/2020] [Accepted: 01/07/2021] [Indexed: 11/17/2022]
Abstract
The InAs/InP quantum dots (QDs) are investigated by time-integrated (PL) and time-resolved photoluminescence (TRPL) experiments. The QDs are fabricated site-selectively by droplet epitaxy technique using block copolymer lithography. The estimated QDs surface density is ∼1.5 × 1010 cm−2. The PL emission at T=300 K is centered at 1.5 μm. Below T=250 K, the PL spectrum shows a fine structure consisting of emission modes attributed to the multimodal QDs size distribution. Temperature-dependent PL reveals negligible carrier transfer among QDs, suggesting good carrier confinement confirmed by theoretical calculations and the TRPL experiment. The PL intensity quench and related energies imply the presence of carrier losses among InP barrier states before carrier capture by QD states. The TRPL experiment highlighted the role of the carrier reservoir in InP. The elongation of PL rise time with temperature imply inefficient carrier capture from the reservoir to QDs. The TRPL experiment at T=15 K reveals the existence of two PL decay components with strong dispersion across the emission spectrum. The decay times dispersion is attributed to different electron-hole confinement regimes for the studied QDs within their broad distribution affected by the size and chemical content inhomogeneities.
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Gajjela RSR, Koenraad PM. Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots. NANOMATERIALS 2021; 11:nano11010085. [PMID: 33401568 PMCID: PMC7823520 DOI: 10.3390/nano11010085] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 01/30/2023]
Abstract
The fundamental understanding of quantum dot (QD) growth mechanism is essential to improve QD based optoelectronic devices. The size, shape, composition, and density of the QDs strongly influence the optoelectronic properties of the QDs. In this article, we present a detailed review on atomic-scale characterization of droplet epitaxy quantum dots by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). We will discuss both strain-free GaAs/AlGaAs QDs and strained InAs/InP QDs grown by droplet epitaxy. The effects of various growth conditions on morphology and composition are presented. The efficiency of methods such as flushing technique is shown by comparing with conventional droplet epitaxy QDs to further gain control over QD height. A detailed characterization of etch pits in both QD systems is provided by X-STM and APT. This review presents an overview of detailed structural and compositional analysis that have assisted in improving the fabrication of QD based optoelectronic devices grown by droplet epitaxy.
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Huang X, Zhong H, Yang J, Liu L, Liu J, Yu Y, Yu S. Morphological engineering of aluminum droplet etched nanoholes for symmetric GaAs quantum dot epitaxy. NANOTECHNOLOGY 2020; 31:495701. [PMID: 32990269 DOI: 10.1088/1361-6528/abb1e9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Symmetric droplet-etched quantum dots (QDs) are the leading candidate for generating high-performance polarization-entangled photon pairs. One of the challenges is how to precisely engineer the properties of QDs by controlling the morphology of etched nanoholes. In this paper, we systematically investigate the influence of the underlying material, showing the morphological evolution of the nanohole structure as well as symmetric GaAs QDs with an average fine-structure splitting (FSS) of (5.9 ± 1.2) μeV. Moreover, we develop a theoretical model that quantitatively reproduces the experimental data and provides insights into the mechanisms governing the relationship between the anisotropy of nanoholes in the [Formula: see text] crystallographic direction and the growth parameters. Our theoretical analysis also indicates how to improve the symmetry of nanoholes to meet the requirements for implementing QDs in entangled photon sources.
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Affiliation(s)
- Xiaoying Huang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Hancheng Zhong
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Jiawei Yang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Lin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Ying Yu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
- Institute for Quantum Information & State Key Laboratory of High Performance Computing, College of Computer, National University of Defense Technology, Changsha 410073, People's Republic of China
| | - Siyuan Yu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
- Photonics Group, Merchant Venturers School of Engineering, University of Bristol, Bristol BS8 1UB, United Kingdom
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40
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Balakirev SV, Solodovnik MS, Eremenko MM, Chernenko NE, Ageev OA. Anomalous behavior of In adatoms during droplet epitaxy on the AlGaAs surfaces. NANOTECHNOLOGY 2020; 31:485604. [PMID: 32931474 DOI: 10.1088/1361-6528/abb15e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Semiconductor quantum dots (QDs) in the InAs/AlGaAs system are of great importance due to their promising optoelectronic and nanophotonic applications. However, control over emission wavelength governed by Al content in the matrix is still limited because of an influence of surface Al content on QD size and density. In this paper, we study the growth of In nanostructures by droplet epitaxy on various AlGaAs surfaces. We demonstrate that an increase in the Al content leads to a decrease in the droplet density and an increase in their size, which contradicts the Stranski-Krastanov QD growth. Using a hybrid analytical-Monte Carlo model, we explain this phenomenon by the fact that In adatoms acquire higher mobility on a first indium monolayer which is bound to surface Al atoms. This assumption is confirmed by the fact that a temperature decrease does not lead to a great increase in the critical thickness of droplet formation on the Al-containing surfaces whereas it changes considerably on the GaAs surface. Furthermore, the Al content influence on the formation of In droplets is much less significant than on the growth of InAs QDs by the Stranski-Krastanov mode. This gives an opportunity to use droplet epitaxy to control the matrix bandgap without considerable influence on the QD characteristics.
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Affiliation(s)
- Sergey V Balakirev
- Department of Nanotechnologies and Microsystems, Institute of Nanotechnologies, Electronics and Equipment Engineering, Southern Federal University, Taganrog 347922, Russia
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41
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Zhai L, Löbl MC, Nguyen GN, Ritzmann J, Javadi A, Spinnler C, Wieck AD, Ludwig A, Warburton RJ. Low-noise GaAs quantum dots for quantum photonics. Nat Commun 2020; 11:4745. [PMID: 32958795 PMCID: PMC7506537 DOI: 10.1038/s41467-020-18625-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 09/03/2020] [Indexed: 11/18/2022] Open
Abstract
Quantum dots are both excellent single-photon sources and hosts for single spins. This combination enables the deterministic generation of Raman-photons—bandwidth-matched to an atomic quantum-memory—and the generation of photon cluster states, a resource in quantum communication and measurement-based quantum computing. GaAs quantum dots in AlGaAs can be matched in frequency to a rubidium-based photon memory, and have potentially improved electron spin coherence compared to the widely used InGaAs quantum dots. However, their charge stability and optical linewidths are typically much worse than for their InGaAs counterparts. Here, we embed GaAs quantum dots into an n-i-p-diode specially designed for low-temperature operation. We demonstrate ultra-low noise behaviour: charge control via Coulomb blockade, close-to lifetime-limited linewidths, and no blinking. We observe high-fidelity optical electron-spin initialisation and long electron-spin lifetimes for these quantum dots. Our work establishes a materials platform for low-noise quantum photonics close to the red part of the spectrum. GaAs quantum dots emitting at the near-red part of the spectrum usually suffers from excess charge-noise. With a careful design of a n-i-p-diode structure hosting GaAs quantum dots, the authors demonstrate ultralow-noise behaviour and high-fidelity spin initialisation close to rubidium wavelengths.
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Affiliation(s)
- Liang Zhai
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
| | - Matthias C Löbl
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Giang N Nguyen
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.,Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, DE-44780, Bochum, Germany
| | - Julian Ritzmann
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, DE-44780, Bochum, Germany
| | - Alisa Javadi
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Clemens Spinnler
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, DE-44780, Bochum, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, DE-44780, Bochum, Germany
| | - Richard J Warburton
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
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42
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Abbarchi M, Mano T, Kuroda T, Sakoda K. Exciton Dynamics in Droplet Epitaxial Quantum Dots Grown on (311)A-Oriented Substrates. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1833. [PMID: 32937876 PMCID: PMC7558330 DOI: 10.3390/nano10091833] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/16/2022]
Abstract
Droplet epitaxy allows the efficient fabrication of a plethora of 3D, III-V-based nanostructures on different crystalline orientations. Quantum dots grown on a (311)A-oriented surface are obtained with record surface density, with or without a wetting layer. These are appealing features for quantum dot lasing, thanks to the large density of quantum emitters and a truly 3D lateral confinement. However, the intimate photophysics of this class of nanostructures has not yet been investigated. Here, we address the main optical and electronic properties of s-shell excitons in individual quantum dots grown on (311)A substrates with photoluminescence spectroscopy experiments. We show the presence of neutral exciton and biexciton as well as positive and negative charged excitons. We investigate the origins of spectral broadening, identifying them in spectral diffusion at low temperature and phonon interaction at higher temperature, the presence of fine interactions between electron and hole spin, and a relevant heavy-hole/light-hole mixing. We interpret the level filling with a simple Poissonian model reproducing the power excitation dependence of the s-shell excitons. These results are relevant for the further improvement of this class of quantum emitters and their exploitation as single-photon sources for low-density samples as well as for efficient lasers for high-density samples.
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Affiliation(s)
- Marco Abbarchi
- Aix Marseille University, Université de Toulon, CNRS, IM2NP Marseille, France
| | - Takaaki Mano
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (K.S.)
| | - Takashi Kuroda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (K.S.)
| | - Kazuaki Sakoda
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; (T.M.); (T.K.); (K.S.)
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Reentrant Behavior of the Density vs. Temperature of Indium Islands on GaAs(111)A. NANOMATERIALS 2020; 10:nano10081512. [PMID: 32752124 PMCID: PMC7466431 DOI: 10.3390/nano10081512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/24/2020] [Accepted: 07/29/2020] [Indexed: 11/17/2022]
Abstract
We show that the density of indium islands on GaAs(111)A substrates have a non-monotonic, reentrant behavior as a function of the indium deposition temperature. The expected increase in the density with decreasing temperature, indeed, is observed only down to 160 ∘C, where the indium islands undertake the expected liquid-to-solid phase transition. Further decreasing the temperature causes a sizable reduction of the island density. An additional reentrant increasing behavior is observed below 80 ∘C. We attribute the above complex behavior to the liquid-solid phase transition and to the complex island-island interaction which takes place between crystalline islands in the presence of strain. Indium solid islands grown at temperatures below 160 ∘C have a face-centered cubic crystal structure.
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Yuan Q, Liang B, Luo S, Wang Y, Yan Q, Wang S, Fu G, Mazur YI, Maidaniuk Y, Ware ME, Salamo GJ. Type-II GaSb quantum dots grown on InAlAs/InP (001) by droplet epitaxy. NANOTECHNOLOGY 2020; 31:315701. [PMID: 32303015 DOI: 10.1088/1361-6528/ab8a8e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
GaSb quantum dots (QDs) have been grown by droplet epitaxy within InAlAs barrier layers on an InP (001) substrate. The droplet growth mode facilitates a larger size (average height ∼4.5 nm) and a lower density (∼6.3 × 109 cm-2) for the QDs than would be expected for the 4% lattice mismatch between GaSb and InAlAs. A type-II band alignment between the GaSb QDs and the InAlAs barriers is revealed by photoluminescence (PL) through a prominent blue-shift of ∼0.11 eV resulting from a six orders of magnitude increase in excitation power. Further confirmation of the type-II nature of these QDs is found through time-resolved PL studies showing a biexponential decay with a long carrier lifetime of ∼10.9 ns. These observations reveal new information for understanding the formation and properties of GaSb/InAlAs/InP QDs, which may be an optimum system for the development of both efficient memory cells and photovoltaic devices.
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Affiliation(s)
- Qing Yuan
- Hebei Key Laboratory of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Baoding 071002, People's Republic of China
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Yeo I, Kim D, Lee KT, Kim JS, Song JD, Park CH, Han IK. Comparative Chemico-Physical Analyses of Strain-Free GaAs/Al 0.3Ga 0.7As Quantum Dots Grown by Droplet Epitaxy. NANOMATERIALS 2020; 10:nano10071301. [PMID: 32630839 PMCID: PMC7407363 DOI: 10.3390/nano10071301] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 11/16/2022]
Abstract
We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0 . 3 Ga 0 . 7 As droplet epitaxy (DE) quantum dots (QDs). By performing comparative analyses of energy-dispersive X-ray spectroscopy with the aid of a three-dimensional (3D) envelope-function model, we elucidate the individual quantum confinement characteristics of the QD band structures with respect to their composition profiles and the asymmetries of their geometrical shapes. By precisely controlling the exciton oscillator strength in strain-free QDs, we envisage the possibility of tailoring light-matter interactions to implement fully integrated quantum photonics based on QD single-photon sources (SPSs).
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Affiliation(s)
- Inah Yeo
- Dielectrics and Advanced Matter Physics Research Center, Pusan National University, Busan 46241, Korea; (D.K.); (C.-H.P.)
- Correspondence: (I.Y.); (I.K.H.)
| | - Doukyun Kim
- Dielectrics and Advanced Matter Physics Research Center, Pusan National University, Busan 46241, Korea; (D.K.); (C.-H.P.)
| | - Kyu-Tae Lee
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea;
| | - Jong Su Kim
- Department of Physics, Yeungnam University, Gyeonsan 38541, Korea;
| | - Jin Dong Song
- Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul 02792, Korea;
| | - Chul-Hong Park
- Dielectrics and Advanced Matter Physics Research Center, Pusan National University, Busan 46241, Korea; (D.K.); (C.-H.P.)
| | - Il Ki Han
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea;
- Correspondence: (I.Y.); (I.K.H.)
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46
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Poborchii V, Bouabdellaoui M, Uchida N, Ronda A, Berbezier I, David T, Ruiz CM, Zazoui M, Sena RP, Abbarchi M, Favre L. Raman microscopy and infrared optical properties of SiGe Mie resonators formed on SiO 2 via Ge condensation and solid state dewetting. NANOTECHNOLOGY 2020; 31:195602. [PMID: 31931487 DOI: 10.1088/1361-6528/ab6ab8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
All-dielectric photonics is a rapidly developing field of optics and material science. The main interest at visible and near-infrared frequencies is light management using high-refractive-index Mie-resonant dielectric particles. Most work in this area of research focuses on exploiting Si-based particles. Here, we study monocrystalline Mie-resonant particles made of Ge-rich SiGe alloys with refractive index higher than that of Si. These islands are formed via solid state dewetting of SiGe flat layers by using two different processes: (i) dewetting of monocrystalline SiGe layers (60%-80% Ge content) obtained via Ge condensation of SiGe on silicon on insulator; and (ii) dewetting of a SiGe layer deposited via molecular beam epitaxy on silicon on insulator and ex situ Ge condensation, forming a Ge-rich shell surrounding a SiGe-core. Using high-spatial-resolution Raman microscopy we monitor Ge content x and strain ϵ of flat layers and SiGe-islands. We observe strain relaxation associated with formation of trading dislocations in the SiGe islands compared to the starting SiGe layers, as confirmed by TEM images. For initial high Ge concentration in the flat layers, the corresponding Ge content in the dewetted islands is lower, owing to diffusion of Si atoms from Si or SiO2 into SiGe islands. The Ge content also varies from particle to particle on the same sample. Size and shape of the dewetted particles depend on the fabrication process: thicker initial SiGe layers lead to larger particles. Samples with narrow island size distribution display rather sharp Mie resonances in the 1000-2500 nm spectral range. Larger islands display Mie resonances at longer wavelength. Positions of the resonances are in agreement with the theoretical calculations in the discrete dipole approximation.
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Affiliation(s)
- Vladimir Poborchii
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, AIST Central-5, Tsukuba 305-8565, Japan
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47
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Maliakkal CB, Mårtensson EK, Tornberg MU, Jacobsson D, Persson AR, Johansson J, Wallenberg LR, Dick KA. Independent Control of Nucleation and Layer Growth in Nanowires. ACS NANO 2020; 14:3868-3875. [PMID: 32049491 PMCID: PMC7307954 DOI: 10.1021/acsnano.9b09816] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/12/2020] [Indexed: 05/10/2023]
Abstract
Control of the crystallization process is central to developing nanomaterials with atomic precision to meet the demands of electronic and quantum technology applications. Semiconductor nanowires grown by the vapor-liquid-solid process are a promising material system in which the ability to form components with structure and composition not achievable in bulk is well-established. Here, we use in situ TEM imaging of Au-catalyzed GaAs nanowire growth to understand the processes by which the growth dynamics are connected to the experimental parameters. We find that two sequential steps in the crystallization process-nucleation and layer growth-can occur on similar time scales and can be controlled independently using different growth parameters. Importantly, the layer growth process contributes significantly to the growth time for all conditions and will play a major role in determining material properties such as compositional uniformity, dopant density, and impurity incorporation. The results are understood through theoretical simulations correlating the growth dynamics, liquid droplet, and experimental parameters. The key insights discussed here are not restricted to Au-catalyzed GaAs nanowire growth but can be extended to most compound nanowire growths in which the different growth species has very different solubility in the catalyst particle.
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Affiliation(s)
- Carina B. Maliakkal
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- Solid
State Physics, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Erik K. Mårtensson
- Solid
State Physics, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Marcus Ulf Tornberg
- Solid
State Physics, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Daniel Jacobsson
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Center for High Resolution Electron Microscopy, Lund University, Box 124, 22100 Lund, Sweden
| | - Axel R. Persson
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Center for High Resolution Electron Microscopy, Lund University, Box 124, 22100 Lund, Sweden
| | - Jonas Johansson
- Solid
State Physics, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
| | - Lars Reine Wallenberg
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
- National
Center for High Resolution Electron Microscopy, Lund University, Box 124, 22100 Lund, Sweden
| | - Kimberly A. Dick
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- Solid
State Physics, Lund University, Box 118, 22100 Lund, Sweden
- NanoLund, Lund University, 22100 Lund, Sweden
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48
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High-temperature droplet epitaxy of symmetric GaAs/AlGaAs quantum dots. Sci Rep 2020; 10:6532. [PMID: 32300114 PMCID: PMC7162903 DOI: 10.1038/s41598-020-62248-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/02/2020] [Indexed: 11/08/2022] Open
Abstract
We introduce a high-temperature droplet epitaxy procedure, based on the control of the arsenization dynamics of nanoscale droplets of liquid Ga on GaAs(111)A surfaces. The use of high temperatures for the self-assembly of droplet epitaxy quantum dots solves major issues related to material defects, introduced during the droplet epitaxy fabrication process, which limited its use for single and entangled photon sources for quantum photonics applications. We identify the region in the parameter space which allows quantum dots to self-assemble with the desired emission wavelength and highly symmetric shape while maintaining a high optical quality. The role of the growth parameters during the droplet arsenization is discussed and modeled.
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49
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Vichi S, Bietti S, Khalili A, Costanzo M, Cappelluti F, Esposito L, Somaschini C, Fedorov A, Tsukamoto S, Rauter P, Sanguinetti S. Droplet epitaxy quantum dot based infrared photodetectors. NANOTECHNOLOGY 2020; 31:245203. [PMID: 32106107 DOI: 10.1088/1361-6528/ab7aa6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The fabrication and characterization of an infrared photodetector based on GaAs droplet epitaxy quantum dots embedded in Al0.3Ga0.7As barrier is reported. The high control over dot electronic properties and the high achievable number density allowed by droplet epitaxy technique permitted us to realize a device using a single dot layer in the active region. Moreover, thanks to the independent control over dot height and width, we were able to obtain a very sharp absorption peak in the thermal infrared region (3-8 μm). Low temperature photocurrent spectrum was measured by Fourier spectroscopy, showing a narrow peak at 198 meV (∼6.3 μm) with a full width at half maximum of 25 meV. The observed absorption is in agreement with theoretical prediction based on effective mass approximation of the dot electronic transition.
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Affiliation(s)
- Stefano Vichi
- LNESS and Department of Materials Science, University of Milano-Bicocca, via Cozzi 55, 20125 Milano, Italy
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50
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Lettner T, Zeuner KD, Schöll E, Huang H, Scharmer S, da Silva SFC, Gyger S, Schweickert L, Rastelli A, Jöns KD, Zwiller V. GaAs Quantum Dot in a Parabolic Microcavity Tuned to 87Rb D 1. ACS PHOTONICS 2020; 7:29-35. [PMID: 32025532 PMCID: PMC6994066 DOI: 10.1021/acsphotonics.9b01243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Indexed: 06/10/2023]
Abstract
We develop a structure to efficiently extract photons emitted by a GaAs quantum dot tuned to rubidium. For this, we employ a broadband microcavity with a curved gold backside mirror that we fabricate by a combination of photoresist reflow, dry reactive ion etching in an inductively coupled plasma, and selective wet chemical etching. Precise reflow and etching control allows us to achieve a parabolic backside mirror with a short focal distance of 265 nm. The fabricated structures yield a predicted (measured) collection efficiency of 63% (12%), an improvement by more than 1 order of magnitude compared to unprocessed samples. We then integrate our quantum dot parabolic microcavities onto a piezoelectric substrate capable of inducing a large in-plane biaxial strain. With this approach, we tune the emission wavelength by 0.5 nm/kV, in a dynamic, reversible, and linear way, to the rubidium D1 line (795 nm).
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Affiliation(s)
- Thomas Lettner
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Katharina D. Zeuner
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Eva Schöll
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Huiying Huang
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University Linz, 4040 Linz, Austria
| | - Selim Scharmer
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | | | - Samuel Gyger
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Lucas Schweickert
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Armando Rastelli
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University Linz, 4040 Linz, Austria
| | - Klaus D. Jöns
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
| | - Val Zwiller
- Department
of Applied Physics, Royal Institute of Technology, Albanova University Centre, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
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