1
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Tuktamyshev A, Vichi S, Cesura FG, Fedorov A, Carminati G, Lambardi D, Pedrini J, Vitiello E, Pezzoli F, Bietti S, Sanguinetti S. Strain Relaxation of InAs Quantum Dots on Misoriented InAlAs(111) Metamorphic Substrates. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3571. [PMID: 36296766 PMCID: PMC9607536 DOI: 10.3390/nano12203571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 09/27/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
We investigate in detail the role of strain relaxation and capping overgrowth in the self-assembly of InAs quantum dots by droplet epitaxy. InAs quantum dots were realized on an In0.6Al0.4As metamorphic buffer layer grown on a GaAs(111)A misoriented substrate. The comparison between the quantum electronic calculations of the optical transitions and the emission properties of the quantum dots highlights the presence of a strong quenching of the emission from larger quantum dots. Detailed analysis of the surface morphology during the capping procedure show the presence of a critical size over which the quantum dots are plastically relaxed.
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Affiliation(s)
- Artur Tuktamyshev
- Isituto Nazionale di Fisica Nucleare, Sezione di Milano-Bicocca, 20100 Milano, Italy
| | - Stefano Vichi
- Isituto Nazionale di Fisica Nucleare, Sezione di Milano-Bicocca, 20100 Milano, Italy
| | | | - Alexey Fedorov
- Centro Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, 20100 Milano, Italy
| | - Giuseppe Carminati
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Davide Lambardi
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Jacopo Pedrini
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Elisa Vitiello
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Fabio Pezzoli
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Sergio Bietti
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
| | - Stefano Sanguinetti
- Isituto Nazionale di Fisica Nucleare, Sezione di Milano-Bicocca, 20100 Milano, Italy
- Department of Materials Science, University of Milano-Bicocca, 20100 Milano, Italy
- Centro Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, 20100 Milano, Italy
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2
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Temperature-Dependent Exciton Dynamics in a Single GaAs Quantum Ring and a Quantum Dot. NANOMATERIALS 2022; 12:nano12142331. [PMID: 35889556 PMCID: PMC9323788 DOI: 10.3390/nano12142331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/23/2022] [Accepted: 06/28/2022] [Indexed: 02/04/2023]
Abstract
Micro-photoluminescence was observed while increasing the excitation power in a single GaAs quantum ring (QR) at 4 K. Fine structures at the energy levels of the ground (N = 1) and excited (N = 2) state excitons exhibited a blue shift when excitation power increased. The excited state exciton had a strong polarization dependence that stemmed from the asymmetric localized state. According to temperature-dependence measurements, strong exciton–phonon interaction (48 meV) was observed from an excited exciton state in comparison with the weak exciton–phonon interaction (27 meV) from the ground exciton state, resulting from enhanced confinement in the excited exciton state. In addition, higher activation energy (by 20 meV) was observed for the confined electrons in a single GaAs QR, where the confinement effect was enhanced by the asymmetric ring structure.
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3
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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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4
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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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5
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Gupta DD, Maiti SK. Can a sample having zero net magnetization produce polarized spin current? JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:505803. [PMID: 32750689 DOI: 10.1088/1361-648x/abac24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
Antiferromagnetic materials can be the suitable functional elements for designing of future spin based electronic devices, circumventing the use of conventional ferromagnetic materials and spin-orbit coupled systems. In the present work first time we put forward the underlying physical mechanism, to the best of our knowledge, to generate polarized spin current through a magnetic material having zero net magnetization. Our proposal is substantiated by considering a 2D geometry which is composed of several concentric 1D rings where neighboring rings are mutually connected with each other. The misalignment of up and down spin bands, which is the primary requirement to have finite spin polarization, is described analytically and then several aspects of spin polarization are studied numerically. Finally, we discuss experimental realization of the proposed magnetic quantum system. Our analysis can be utilized to any other complicated magnetic geometries, and may open up a new platform for future spintronic applications.
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Affiliation(s)
- Debjani Das Gupta
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108, India
| | - Santanu K Maiti
- Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108, India
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6
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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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7
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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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8
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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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9
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Shahnazaryan V, Mughnetsyan V, Shelykh I, Sarkisyan H. Exciton-Exciton Interactions in Coaxial Double Quantum Rings. NANOMATERIALS 2019; 9:nano9101469. [PMID: 31623195 PMCID: PMC6836289 DOI: 10.3390/nano9101469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/07/2019] [Accepted: 10/13/2019] [Indexed: 11/16/2022]
Abstract
We study theoretically the quantum states of two interacting excitons in coaxial double quantum rings. An interplay between exciton–exciton Coulomb interactions and specific geometry of the structure leads to the emergence of peculiar energy spectrum of two exciton system. We develop a semi-analytic approach providing highly accurate energies of system in the wide range of values of geometrical parameters relevant to experimental realizations.
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Affiliation(s)
- Vanik Shahnazaryan
- Faculty of Physics and Engineering, ITMO University, 197101 St. Petersburg, Russia.
| | - Vram Mughnetsyan
- Faculty of Physics, Yerevan State University, Yerevan 0025, Armenia.
| | - Ivan Shelykh
- Faculty of Physics and Engineering, ITMO University, 197101 St. Petersburg, Russia.
- Science Institute, University of Iceland, IS-107 Reykjavik, Iceland.
| | - Hayk Sarkisyan
- Faculty of Physics, Yerevan State University, Yerevan 0025, Armenia.
- Institute of Engineering and Physics, Russian-Armenian (Slavonic) University, Yerevan 0026, Armenia.
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10
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Gurioli M, Wang Z, Rastelli A, Kuroda T, Sanguinetti S. Droplet epitaxy of semiconductor nanostructures for quantum photonic devices. NATURE MATERIALS 2019; 18:799-810. [PMID: 31086322 DOI: 10.1038/s41563-019-0355-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/22/2019] [Indexed: 05/25/2023]
Abstract
The long dreamed 'quantum internet' would consist of a network of quantum nodes (solid-state or atomic systems) linked by flying qubits, naturally based on photons, travelling over long distances at the speed of light, with negligible decoherence. A key component is a light source, able to provide single or entangled photon pairs. Among the different platforms, semiconductor quantum dots (QDs) are very attractive, as they can be integrated with other photonic and electronic components in miniaturized chips. In the early 1990s two approaches were developed to synthetize self-assembled epitaxial semiconductor QDs, or 'artificial atoms'-namely, the Stranski-Krastanov (SK) and the droplet epitaxy (DE) methods. Because of its robustness and simplicity, the SK method became the workhorse to achieve several breakthroughs in both fundamental and technological areas. The need for specific emission wavelengths or structural and optical properties has nevertheless motivated further research on the DE method and its more recent development, local droplet etching (LDE), as complementary routes to obtain high-quality semiconductor nanostructures. The recent reports on the generation of highly entangled photon pairs, combined with good photon indistinguishability, suggest that DE and LDE QDs may complement (and sometimes even outperform) conventional SK InGaAs QDs as quantum emitters. We present here a critical survey of the state of the art of DE and LDE, highlighting the advantages and weaknesses, the achievements and challenges that are still open, in view of applications in quantum communication and technology.
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Affiliation(s)
| | - Zhiming Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, China
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11
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Niu YR, Pereiro J, Gomez D, Jesson DE. Selected energy dark-field imaging using low energy electrons for optimal surface phase discrimination. Ultramicroscopy 2019; 200:79-83. [PMID: 30836287 DOI: 10.1016/j.ultramic.2019.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/18/2019] [Indexed: 11/27/2022]
Abstract
We propose a general strategy for surface phase discrimination by dark-field imaging using low energy electrons, which maximizes contrast using diffraction spots, at selected optimal energies. The method can be automated to produce composite phase maps in real space and study the dynamics of complex phase transformations in real-time. To illustrate the capabilities of the technique, surface phases are mapped in the vicinity of liquid Ga droplets on the technologically important GaAs (001) surface.
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Affiliation(s)
- Y R Niu
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom.
| | - J Pereiro
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom
| | - D Gomez
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom
| | - D E Jesson
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom
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12
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Mailleur A, Pirat C, Pierre-Louis O, Colombani J. Hollow Rims from Water Drop Evaporation on Salt Substrates. PHYSICAL REVIEW LETTERS 2018; 121:214501. [PMID: 30517808 DOI: 10.1103/physrevlett.121.214501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/03/2018] [Indexed: 05/27/2023]
Abstract
We report on the observation of thin salt shells that form at the periphery of evaporating pure water drops on salt. Shell shapes range from rings of inclined walls to hollow toroidal rims. We interpret this phenomenon as a consequence of a molecular coffee-stain effect by which the dissolved salt is advected toward the pinned contact line where an increased evaporation takes place. The subsequent salt supersaturation in the vicinity of the triple line drives the crystallization of the shell at the liquid-air interface. This interpretation is supported by a simple model for shell growth.
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Affiliation(s)
- Alexandra Mailleur
- Institut Lumière Matière; Université de Lyon; Université Claude Bernard Lyon 1; CNRS UMR 5306; Domaine scientifique de la Doua, F-69622 Villeurbanne, France
| | - Christophe Pirat
- Institut Lumière Matière; Université de Lyon; Université Claude Bernard Lyon 1; CNRS UMR 5306; Domaine scientifique de la Doua, F-69622 Villeurbanne, France
| | - Olivier Pierre-Louis
- Institut Lumière Matière; Université de Lyon; Université Claude Bernard Lyon 1; CNRS UMR 5306; Domaine scientifique de la Doua, F-69622 Villeurbanne, France
| | - Jean Colombani
- Institut Lumière Matière; Université de Lyon; Université Claude Bernard Lyon 1; CNRS UMR 5306; Domaine scientifique de la Doua, F-69622 Villeurbanne, France
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13
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Park SI, Trojak OJ, Lee E, Song JD, Kyhm J, Han I, Kim J, Yi GC, Sapienza L. GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications. NANOTECHNOLOGY 2018; 29:205602. [PMID: 29488899 DOI: 10.1088/1361-6528/aab2e1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the growth and optical characterization of droplet GaAs quantum dots (QDs) with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the QDs obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single QDs, at visible wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are good candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications.
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Affiliation(s)
- Suk In Park
- Center for Opto-Electronic Materials and Devices Research, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea. Department of Physics and Astronomy, Seoul National University, Seoul 08-826, Republic of Korea
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14
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Modeling of anisotropic properties of double quantum rings by the terahertz laser field. Sci Rep 2018; 8:6145. [PMID: 29670157 PMCID: PMC5906452 DOI: 10.1038/s41598-018-24494-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/01/2018] [Indexed: 11/12/2022] Open
Abstract
The rendering of different shapes of just a single sample of a concentric double quantum ring is demonstrated realizable with a terahertz laser field, that in turn, allows the manipulation of electronic and optical properties of a sample. It is shown that by changing the intensity or frequency of laser field, one can come to a new set of degenerated levels in double quantum rings and switch the charge distribution between the rings. In addition, depending on the direction of an additional static electric field, the linear and quadratic quantum confined Stark effects are observed. The absorption spectrum shifts and the additive absorption coefficient variations affected by laser and electric fields are discussed. Finally, anisotropic electronic and optical properties of isotropic concentric double quantum rings are modeled with the help of terahertz laser field.
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15
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Kennedy SM, Zheng CX, Jesson DE. Droplet Epitaxy Image Contrast in Mirror Electron Microscopy. NANOSCALE RESEARCH LETTERS 2017; 12:68. [PMID: 28116613 PMCID: PMC5256635 DOI: 10.1186/s11671-017-1837-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 01/09/2017] [Indexed: 06/02/2023]
Abstract
Image simulation methods are applied to interpret mirror electron microscopy (MEM) images obtained from a movie of GaAs droplet epitaxy. Cylindrical symmetry of structures grown by droplet epitaxy is assumed in the simulations which reproduce the main features of the experimental MEM image contrast, demonstrating that droplet epitaxy can be studied in real-time. It is therefore confirmed that an inner ring forms at the droplet contact line and an outer ring (or skirt) occurs outside the droplet periphery. We believe that MEM combined with image simulations will be increasingly used to study the formation and growth of quantum structures.
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Affiliation(s)
- S. M. Kennedy
- School of Physics, Monash University, Melbourne, Victoria 3800 Australia
| | - C. X. Zheng
- Department of Civil Engineering, Monash University, Melbourne, Victoria 3800 Australia
| | - D. E. Jesson
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA UK
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16
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Yao Y, Elborg M, Kuroda T, Sakoda K. Excitonic Aharonov-Bohm effect in QD-on-ring nanostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:385301. [PMID: 28661406 DOI: 10.1088/1361-648x/aa7c90] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We show by the first-order perturbation theory and the configuration interaction method that the Coulomb interaction in quantum rings mixes electron-hole pair states with the same total angular momentum, which makes it difficult to observe a clear excitonic Aharonov-Bohm (A-B) effect. To avoid this situation, we propose the use of a combined structure of a quantum dot on the top of a quantum ring with an applied static electric field. Under moderate experimental conditions with respect to the applied electric and magnetic fields, we show that we can observe the excitonic A-B effect due to the reduction of the Coulomb interaction and an increase in the difference between the average radii of the electron and hole trajectories.
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Affiliation(s)
- Yuanzhao Yao
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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17
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Molecular spectrum of laterally coupled quantum rings under intense terahertz radiation. Sci Rep 2017; 7:10485. [PMID: 28874715 PMCID: PMC5585341 DOI: 10.1038/s41598-017-10877-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 08/11/2017] [Indexed: 11/09/2022] Open
Abstract
We study the influence of intense THz laser radiation and electric field on molecular states of laterally coupled quantum rings. Laser radiation shows the capability to dissociate quantum ring molecule and add 2-fold degeneracy to the molecular states at the fixed value of the overlapping size between rings. It is shown that coupled to decoupled molecular states phase transition points form almost a straight line with a slope equal to two. In addition, the electric field direction dependent energy spectrum shows unexpected oscillations, demonstrating strong coupling between molecular states. Besides, intraband absorption is considered, showing both blue and redshifts in its spectrum. The obtained results can be useful for the controlling of degeneracy of the discrete energy spectrum of nanoscale structures and in the tunneling effects therein.
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18
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Scarpellini D, Fedorov A, Somaschini C, Frigeri C, Bollani M, Bietti S, Nöetzel R, Sanguinetti S. Ga crystallization dynamics during annealing of self-assisted GaAs nanowires. NANOTECHNOLOGY 2017; 28:045605. [PMID: 27997367 DOI: 10.1088/1361-6528/28/4/045605] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In As atmosphere, we analyzed the crystallization dynamics during post-growth annealing of Ga droplets residing at the top of self-assisted GaAs nanowires grown by molecular beam epitaxy. The final crystallization steps, fundamental to determining the top facet nanowire morphology, proceeded via a balance of Ga crystallization via vapor-liquid-solid and layer-by-layer growth around the droplet, promoted by Ga diffusion out of the droplet perimeter, As desorption, and diffusion dynamics. By controlling As flux and substrate temperature the transformation of Ga droplets into nanowire segments with a top surface flat and parallel to the substrate was achieved, thus opening the possibility to realize atomically sharp vertical heterostructures in III-As self-assisted nanowires through group III exchange.
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Affiliation(s)
- David Scarpellini
- LNESS and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milano, Italy
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19
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Heyn C, Zocher M, Schnüll S, Hansen W. Role of Arsenic During Aluminum Droplet Etching of Nanoholes in AlGaAs. NANOSCALE RESEARCH LETTERS 2016; 11:428. [PMID: 27671015 PMCID: PMC5037105 DOI: 10.1186/s11671-016-1648-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 09/20/2016] [Indexed: 06/06/2023]
Abstract
Self-assembled nanoholes are drilled into (001) AlGaAs surfaces during molecular beam epitaxy (MBE) using local droplet etching (LDE) with Al droplets. It is known that this process requires a small amount of background arsenic for droplet material removal. The present work demonstrates that the As background can be supplied by both a small As flux to the surface as well as by the topmost As layer in an As-terminated surface reconstruction acting as a reservoir. We study the temperature-dependent evaporation of the As topmost layer with in situ electron diffraction and determine an activation energy of 2.49 eV. After thermal removal of the As topmost layer droplet etching is studied under well-defined As supply. We observe with decreasing As flux four regimes: planar growth, uniform nanoholes, non-uniform holes, and droplet conservation. The influence of the As supply is discussed quantitatively on the basis of a kinetic rate model.
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Affiliation(s)
- Christian Heyn
- Institut für Nanostruktur- und Festkörperphysik, Center for Hybrid Nanostructures (CHYN), Universität Hamburg, Jungiusstraße 11, Hamburg, D-20355 Germany
| | - Michel Zocher
- Institut für Nanostruktur- und Festkörperphysik, Center for Hybrid Nanostructures (CHYN), Universität Hamburg, Jungiusstraße 11, Hamburg, D-20355 Germany
| | - Sandra Schnüll
- Institut für Nanostruktur- und Festkörperphysik, Center for Hybrid Nanostructures (CHYN), Universität Hamburg, Jungiusstraße 11, Hamburg, D-20355 Germany
| | - Wolfgang Hansen
- Institut für Nanostruktur- und Festkörperphysik, Center for Hybrid Nanostructures (CHYN), Universität Hamburg, Jungiusstraße 11, Hamburg, D-20355 Germany
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20
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Xu X, Wu J, Wang X, Zhang M, Li J, Shi Z, Li H, Zhou Z, Ji H, Niu X, Wang ZM. Ion-Beam-Directed Self-Ordering of Ga Nanodroplets on GaAs Surfaces. NANOSCALE RESEARCH LETTERS 2016; 11:38. [PMID: 26815607 PMCID: PMC4729756 DOI: 10.1186/s11671-016-1234-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/05/2016] [Indexed: 06/05/2023]
Abstract
Ordered nanodroplet arrays and aligned nanodroplet chains are fabricated using ion-beam-directed self-organization. The morphological evolution of nanodroplets formed on GaAs (100) substrates under ion beam bombardment is characterized by scanning electron microscopy and atomic force microscopy. Ordered Ga nanodroplets are self-assembled under ion beam bombardment at off-normal incidence angles. The uniformity, size, and density of Ga nanodroplets can be tuned by the incident angles of ion beam. The ion beam current also plays a critical role in the self-ordering of Ga nanodroplets, and it is found that the droplets exhibit a similar droplet size but higher density and better uniformity with increasing the ion beam current. In addition, more complex arrangements of nanodroplets are achieved via in situ patterning and ion-beam-directed migration of Ga atoms. Particularly, compared to the destructive formation of nanodroplets through direct ion beam bombardment, the controllable assembly of nanodroplets on intact surfaces can be used as templates for fabrication of ordered semiconductor nanostructures by droplet epitaxy.
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Affiliation(s)
- Xingliang Xu
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
- Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
- Research Center for Microsystems and Terahertz, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
- Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing, 100083, People's Republic of China
| | - Jiang Wu
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
- Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK
| | - Xiaodong Wang
- Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing, 100083, People's Republic of China
| | - Mingliang Zhang
- Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing, 100083, People's Republic of China
| | - Juntao Li
- Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
- Research Center for Microsystems and Terahertz, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
| | - Zhigui Shi
- Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
- Research Center for Microsystems and Terahertz, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China
| | - Handong Li
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Zhihua Zhou
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Haining Ji
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Xiaobin Niu
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China
| | - Zhiming M Wang
- Institute of Fundamental and Frontier Science, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
- Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing, 100083, People's Republic of China.
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21
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Bioud YA, Boucherif A, Belarouci A, Paradis E, Drouin D, Arès R. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs. NANOSCALE RESEARCH LETTERS 2016; 11:446. [PMID: 27704487 PMCID: PMC5050177 DOI: 10.1186/s11671-016-1642-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 09/20/2016] [Indexed: 05/30/2023]
Abstract
We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.
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Affiliation(s)
- Youcef A. Bioud
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
| | - Abderraouf Boucherif
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
| | - Ali Belarouci
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
| | - Etienne Paradis
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
| | - Dominique Drouin
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
| | - Richard Arès
- Laboratoire Nanotechnologies Nanosystèmes (LN2)—CNRS UMI-3463, Institut Interdisciplinaire d’Innovation Technologique (3IT), Université de Sherbrooke, 3000 Boulevard Université, Sherbrooke, J1K OA5 Québec Canada
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22
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Liu H, Jin Y, Yang C. Droplet-induced dot, dot-in-hole, and hole structures in GaGe thin films grown by MOCVD on GaAs substrates. CrystEngComm 2016. [DOI: 10.1039/c6ce00778c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Li MY, Sui M, Pandey P, Zhang Q, Kim ES, Lee J. Systematic Control of Self-Assembled Au Nanoparticles and Nanostructures Through the Variation of Deposition Amount, Annealing Duration, and Temperature on Si (111). NANOSCALE RESEARCH LETTERS 2015; 10:380. [PMID: 26428015 PMCID: PMC4883281 DOI: 10.1186/s11671-015-1084-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 09/21/2015] [Indexed: 05/18/2023]
Abstract
The size, density, and configurations of Au nanoparticles (NPs) can play important roles in controlling the electron mobility, light absorption, and localized surface plasmon resonance, and further in the Au NP-assisted nanostructure fabrications. In this study, we present a systematical investigation on the evolution of Au NPs and nanostructures on Si (111) by controlling the deposition amount (DA), annealing temperature (AT), and dwelling time (DT). Under an identical growth condition, the morphologies of Au NPs and nanostructures drastically evolve when the DA is only slightly varied, based on the Volmer-Weber and coalescence models: i.e. I: mini NPs, II: mid-sized round dome-shaped Au NPs, III: large Au NPs, and IV: coalesced nanostructures. With the AT control, three distinctive ranges are observed: i.e., NP nucleation, Au NPs maturation and melting. The gradual dimensional expansion of Au NPs is always compensated with the density reduction, which is explained with the thermodynamic theory. The DT effect is relatively minor on Au NPs, a sharp contrast to other metallic NPs, which is discussed based on the Ostwald-ripening.
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Affiliation(s)
- Ming-Yu Li
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea
| | - Mao Sui
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea
| | - Puran Pandey
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea
| | - Quanzhen Zhang
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea
| | - Eun-Soo Kim
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea
| | - Jihoon Lee
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.
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24
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Dubrovskii VG, Xu T, Álvarez AD, Plissard SR, Caroff P, Glas F, Grandidier B. Self-Equilibration of the Diameter of Ga-Catalyzed GaAs Nanowires. NANO LETTERS 2015; 15:5580-4. [PMID: 26189571 DOI: 10.1021/acs.nanolett.5b02226] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Designing strategies to reach monodispersity in fabrication of semiconductor nanowire ensembles is essential for numerous applications. When Ga-catalyzed GaAs nanowire arrays are grown by molecular beam epitaxy with help of droplet-engineering, we observe a significant narrowing of the diameter distribution of the final nanowire array with respect to the size distribution of the initial Ga droplets. Considering that the droplet serves as a nonequilibrium reservoir of a group III metal, we develop a model that demonstrates a self-equilibration effect on the droplet size in self-catalyzed III-V nanowires. This effect leads to arrays of nanowires with a high degree of uniformity regardless of the initial conditions, while the stationary diameter can be further finely tuned by varying the spacing of the array pitch on patterned Si substrates.
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Affiliation(s)
- V G Dubrovskii
- †St. Petersburg Academic University, Khlopina 8/3, 194021, St. Petersburg, Russia
- ‡Ioffe Physical Technical Institute RAS, Politekhnicheskaya 26, 194021, St. Petersburg, Russia
- §ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg, Russia
| | - T Xu
- ∥Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520, Département ISEN, 41 bd Vauban, 59046 Lille Cedex, France
- ⊥Sino-European School of Technology, Shanghai University, 99 Shangda Road, Shanghai, 200444, People's Republic of China
| | - A Díaz Álvarez
- ∥Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520, Département ISEN, 41 bd Vauban, 59046 Lille Cedex, France
| | - S R Plissard
- ∥Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520, Département ISEN, 41 bd Vauban, 59046 Lille Cedex, France
- #CNRS-Laboratoire d'Analyse et d'Architecture des Systèmes (LAAS), Université de Toulouse, 7 avenue du colonel Roche, 31400 Toulouse, France
| | - P Caroff
- ∥Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520, Département ISEN, 41 bd Vauban, 59046 Lille Cedex, France
- ∇Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia
| | - F Glas
- ○CNRS-Laboratoire de Photonique et de Nanostructures (LPN), Route de Nozay, 91460 Marcoussis, France
| | - B Grandidier
- ∥Institut d'Electronique, de Microélectronique et de Nanotechnologies (IEMN), CNRS, UMR 8520, Département ISEN, 41 bd Vauban, 59046 Lille Cedex, France
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25
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Lee EH, Song JD, Han IK, Chang SK, Langer F, Höfling S, Forchel A, Kamp M, Kim JS. Structural and optical properties of position-retrievable low-density GaAs droplet epitaxial quantum dots for application to single photon sources with plasmonic optical coupling. NANOSCALE RESEARCH LETTERS 2015; 10:114. [PMID: 25852409 PMCID: PMC4385222 DOI: 10.1186/s11671-015-0826-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 02/17/2015] [Indexed: 06/04/2023]
Abstract
The position of a single GaAs quantum dot (QD), which is optically active, grown by low-density droplet epitaxy (DE) (approximately 4 QDs/μm(2)), was directly observed on the surface of a 45-nm-thick Al0.3Ga0.7As capping layer. The thin thickness of AlGaAs capping layer is useful for single photon sources with plasmonic optical coupling. A micro-photoluminescence for GaAs DE QDs has shown exciton/biexciton behavior in the range of 1.654 to 1.657 eV. The direct observation of positions of low-density GaAs DE QDs would be advantageous for mass fabrication of devices that use a single QD, such as single photon sources.
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Affiliation(s)
- Eun-Hye Lee
- />Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 136-791 South Korea
- />Institute of Physics and Applied Physics, Yonsei University, Seoul, 120-749 South Korea
| | - Jin-Dong Song
- />Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 136-791 South Korea
| | - Il-Ki Han
- />Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul, 136-791 South Korea
| | - Soo-Kyung Chang
- />Institute of Physics and Applied Physics, Yonsei University, Seoul, 120-749 South Korea
| | - Fabian Langer
- />Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sven Höfling
- />Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Alfred Forchel
- />Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Martin Kamp
- />Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jong-Su Kim
- />Department of Physics, Yeungnam University, Gyeongsangbuk-Do, 712-749 South Korea
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26
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Li X, Wu J, Wang ZM, Liang B, Lee J, Kim ES, Salamo GJ. Origin of nanohole formation by etching based on droplet epitaxy. NANOSCALE 2014; 6:2675-2681. [PMID: 24445506 DOI: 10.1039/c3nr06064k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Creating and manipulating materials at the nanoscale with controllable size, shape and nucleation site is an important task to meet the urgent demands for quantum structures with designed properties. In the last ten years, droplet epitaxy has been emerging as a versatile fabrication method for various complex nanostructures, such as quantum dots, quantum rings, double-rings, and so on. However, there is a lack of understanding of the deep nanohole formation based on droplet epitaxy at a high substrate temperature. Here we fabricate self-organized GaAs nanoholes by Ga droplet etching at high temperature based on droplet epitaxy, and they present good optoelectronic properties and have promising applications in fabrication of nanodevices due to their unique topology. A theoretical model is correspondingly proposed to explain the basic mechanism and simulate the time evolution of the nanohole structures. Our analysis shows that the morphology of the nanohole nanostructures can be well controlled through regulating experimental conditions.
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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, P. R. China.
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27
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Persichetti L, Sgarlata A, Fanfoni M, Balzarotti A. The entangled role of strain and diffusion in driving the spontaneous formation of atolls and holes in Ge/Si(111) heteroepitaxy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:395801. [PMID: 23999271 DOI: 10.1088/0953-8984/25/39/395801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate the interdependent processes of strain and diffusion in the formation of holes and atolls obtained by rapid annealing of Ge/Si(111) islands at T ≈ 970 °C. We show that the shape evolution from islands to atolls and holes is closely captured by an analytical model including strain-driven diffusion. In the model, strain profiles obtained by finite element solutions of continuum elasticity equations are introduced in the diffusion equation as the source of a diffusion flux driven by the strain gradient. When the shape of the elastic field in Ge/Si(111) islands is coupled to diffusion, the morphology of the SiGe nanostructures observed after annealing is reproduced.
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Affiliation(s)
- L Persichetti
- Dipartimento di Fisica, Università di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, I-00133 Roma, Italy. CHOSE (Centre for Hybrid and Organic Solar Energy), Dipartimento di Ingegneria Elettronica Università di Roma 'Tor Vergata', Via del Politecnico 1, I-00133 Roma, Italy
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28
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Somaschini C, Bietti S, Trampert A, Jahn U, Hauswald C, Riechert H, Sanguinetti S, Geelhaar L. Control over the number density and diameter of GaAs nanowires on Si(111) mediated by droplet epitaxy. NANO LETTERS 2013; 13:3607-3613. [PMID: 23898953 DOI: 10.1021/nl401404w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a novel approach for the growth of GaAs nanowires (NWs) with controllable number density and diameter, which consists of the combination between droplet epitaxy (DE) and self-assisted NW growth. In our method, GaAs islands are initially formed on Si(111) by DE and, subsequently, GaAs NWs are selectively grown on their top facet, which acts as a nucleation site. By DE, we can successfully tailor the number density and diameter of the template of initial GaAs islands and the same degree of control is transferred to the final GaAs NWs. We show how, by a suitable choice of V/III flux ratio, a single NW can be accommodated on top of each GaAs base island. By transmission electron microscopy, as well as cathodo- and photoluminescence spectroscopy, we confirmed the high structural and optical quality of GaAs NWs grown by our method. We believe that this combined approach can be more generally applied to the fabrication of different homo- or heteroepitaxial NWs, nucleated on the top of predefined islands obtained by DE.
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29
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Zhou ZY, Zheng CX, Tang WX, Tersoff J, Jesson DE. Origin of quantum ring formation during droplet epitaxy. PHYSICAL REVIEW LETTERS 2013; 111:036102. [PMID: 23909340 DOI: 10.1103/physrevlett.111.036102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 05/16/2023]
Abstract
Droplet epitaxy of GaAs is studied in real time using in situ surface electron microscopy. The resulting movies motivate a theoretical model for quantum ring formation which can explain the origin of nanoscale features such as double rings observed under a variety of experimental conditions. Inner rings correspond to GaAs deposition at the droplet edge, while outer rings result from the reaction of Ga and As atoms diffusing along the surface. The observed variety of morphologies primarily reflects relative changes in the outer rings with temperature and As flux.
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Affiliation(s)
- Z Y Zhou
- School of Physics, Monash University, Victoria 3800, Australia
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30
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Bietti S, Somaschini C, Sanguinetti S. Crystallization kinetics of Ga metallic nano-droplets under As flux. NANOTECHNOLOGY 2013; 24:205603. [PMID: 23609489 DOI: 10.1088/0957-4484/24/20/205603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present an experimental investigation of the crystallization dynamics of Ga nano-droplets under As flux. The transformation of the metallic Ga contained in the droplets into a GaAs nano-island proceeds by increasing the size of a tiny ring of GaAs which is formed just after the Ga deposition at the rim of a droplet. The GaAs crystallization rate depends linearly on the liquid-solid interface area. The maximum growth rate is set by the As flux impinging on the droplet, thus showing an efficient As incorporation and transport despite the predicted low solubility of the As in metallic Ga at the crystallization temperatures.
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Affiliation(s)
- S Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy
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31
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Bietti S, Sanguinetti S. Controlled suppression of the photoluminescence superlinear dependence on excitation density in quantum dots. NANOSCALE RESEARCH LETTERS 2012; 7:551. [PMID: 23033918 PMCID: PMC3497608 DOI: 10.1186/1556-276x-7-551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 09/21/2012] [Indexed: 06/01/2023]
Abstract
: We have shown that it is possible to tune, up to complete suppression, the photoluminescence superlinear dependence on the excitation density in quantum dot samples at high temperatures by annealing treatments. The effect has been attributed to the reduction of the defectivity of the material induced by annealing.
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Affiliation(s)
- Sergio Bietti
- LNESS and Dipartimento di Scienza dei Materiali, Universitá di Milano-Bicocca, Via Cozzi 53, Milano, I-20125, Italy
| | - Stefano Sanguinetti
- LNESS and Dipartimento di Scienza dei Materiali, Universitá di Milano-Bicocca, Via Cozzi 53, Milano, I-20125, Italy
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Li MY, Hirono Y, Koukourinkova SD, Sui M, Song S, Kim ES, Lee J, Salamo GJ. Formation of Ga droplets on patterned GaAs (100) by molecular beam epitaxy. NANOSCALE RESEARCH LETTERS 2012; 7:550. [PMID: 23033893 PMCID: PMC3506476 DOI: 10.1186/1556-276x-7-550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 09/17/2012] [Indexed: 06/01/2023]
Abstract
In this paper, the formation of Ga droplets on photo-lithographically patterned GaAs (100) and the control of the size and density of Ga droplets by droplet epitaxy using molecular beam epitaxy are demonstrated. In extension of our previous result from the journal Physical Status Solidi A, volume 209 in 2012, the sharp contrast of the size and density of Ga droplets is clearly observed by high-resolution scanning electron microscope, atomic force microscope, and energy dispersive X-ray spectrometry. Also, additional monolayer (ML) coverage is added to strength the result. The density of droplets is an order of magnitude higher on the trench area (etched area), while the size of droplets is much larger on the strip top area (un-etched area). A systematic variation of ML coverage results in an establishment of the control of size and density of Ga droplets. The cross-sectional line profile analysis and root mean square roughness analysis show that the trench area (etched area) is approximately six times rougher. The atomic surface roughness is suggested to be the main cause of the sharp contrast of the size and density of Ga droplets and is discussed in terms of surface diffusion.
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Affiliation(s)
- Ming-Yu Li
- College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
| | - Yusuke Hirono
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville 72701, AR, USA
| | - Sabina D Koukourinkova
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville 72701, AR, USA
| | - Mao Sui
- College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
| | - Sangmin Song
- College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
| | - Eun-Soo Kim
- College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
| | - Jihoon Lee
- College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville 72701, AR, USA
| | - Gregory J Salamo
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville 72701, AR, USA
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33
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Wu HD, Xiao Y, Pan GB. Micro rings self-assembled from organic NPB and their polarized optical properties. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.08.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Cavigli L, Bietti S, Abbarchi M, Somaschini C, Vinattieri A, Gurioli M, Fedorov A, Isella G, Grilli E, Sanguinetti S. Fast emission dynamics in droplet epitaxy GaAs ring-disk nanostructures integrated on Si. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:104017. [PMID: 22353556 DOI: 10.1088/0953-8984/24/10/104017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The emission dynamics in GaAs/AlGaAs coupled ring-disk (CRD) quantum structures fabricated on silicon substrates is presented. The CRD structures are self-assembled via droplet epitaxy, a growth technique which, due to its low thermal budget, is compatible with the monolithic integration of III-V devices on Si based electronic circuits. Continuous wave, time resolved photoluminescence and theoretical calculations in the effective mass approximations are presented for the assessment of the electronic and carrier properties of the CRDs. The CRDs show a fast carrier dynamics which is expected to be suitable for ultrafast optical switching applications integrated on silicon.
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Affiliation(s)
- L Cavigli
- LENS and Dipartimento di Fisica, Universitá di Firenze, Via Sansone 1, I-50019, Sesto Fiorentino, Italy
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Lyamkina AA, Dmitriev DV, Galitsyn YG, Kesler VG, Moshchenko SP, Toropov AI. The Investigation of Intermediate Stage of Template Etching with Metal Droplets by Wetting Angle Analysis on (001) GaAs Surface. NANOSCALE RESEARCH LETTERS 2011; 6:42. [PMID: 27502664 PMCID: PMC3211836 DOI: 10.1007/s11671-010-9790-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 09/09/2010] [Indexed: 06/06/2023]
Abstract
In this work, we study metal droplets on a semiconductor surface that are the initial stage for both droplet epitaxy and local droplet etching. The distributions of droplet geometrical parameters such as height, radius and volume help to understand the droplet formation that strongly influences subsequent nanohole etching. To investigate the etching and intermixing processes, we offer a new method of wetting angle analysis. The aspect ratio that is defined as the ratio of the height to radius was used as an estimation of wetting angle which depends on the droplet material. The investigation of the wetting angle and the estimation of indium content revealed significant materials intermixing during the deposition time. AFM measurements reveal the presence of two droplet groups that is in agreement with nanohole investigations. To explain this observation, we consider arsenic evaporation and consequent change in the initial substrate. On the basis of our analysis, we suggest the model of droplet evolution and the formation of two droplet groups.
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Affiliation(s)
- A A Lyamkina
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia.
- Novosibirsk State University, Pirogova 2, 630090, Novosibirsk, Russia.
| | - D V Dmitriev
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia
| | - Yu G Galitsyn
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia
| | - V G Kesler
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia
| | - S P Moshchenko
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia
| | - A I Toropov
- Rzhanov Institute of Semiconductor Physics SB RAS, Acad. Lavrent'eva Ave. 13, 630090, Novosibirsk, Russia
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36
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Wan L, Li L, Mao G. Nanospiral Formation by Droplet Drying: One Molecule at a Time. NANOSCALE RESEARCH LETTERS 2011; 6:49. [PMID: 27502671 PMCID: PMC3212004 DOI: 10.1007/s11671-010-9793-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 09/09/2010] [Indexed: 06/06/2023]
Abstract
We have created nanospirals by self-assembly during droplet evaporation. The nanospirals, 60-70 nm in diameter, formed when solvent mixtures of methanol and m-cresol were used. In contrast, spin coating using only methanol as the solvent produced epitaxial films of stripe nanopatterns and using only m-cresol disordered structure. Due to the disparity in vapor pressure between the two solvents, droplets of m-cresol solution remaining on the substrate serve as templates for the self-assembly of carboxylic acid molecules, which in turn allows the visualization of solution droplet evaporation one molecule at a time.
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Affiliation(s)
- Lei Wan
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, Michigan, 48202, USA
| | - Li Li
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, Michigan, 48202, USA
| | - Guangzhao Mao
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, Michigan, 48202, USA.
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37
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Surface x-ray diffraction results on the III-V droplet heteroepitaxy growth process for quantum dots: recent understanding and open questions. SENSORS 2011; 11:10624-37. [PMID: 22346663 PMCID: PMC3274305 DOI: 10.3390/s111110624] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 10/25/2011] [Accepted: 11/02/2011] [Indexed: 11/19/2022]
Abstract
In recent years, epitaxial growth of self-assembled quantum dots has offered a way to incorporate new properties into existing solid state devices. Although the droplet heteroepitaxy method is relatively complex, it is quite relaxed with respect to the material combinations that can be used. This offers great flexibility in the systems that can be achieved. In this paper we review the structure and composition of a number of quantum dot systems grown by the droplet heteroepitaxy method, emphasizing the insights that these experiments provide with respect to the growth process. Detailed structural and composition information has been obtained using surface X-ray diffraction analyzed by the COBRA phase retrieval method. A number of interesting phenomena have been observed: penetration of the dots into the substrate (“nano-drilling”) is often encountered; interdiffusion and intermixing already start when the group III droplets are deposited, and structure and composition may be very different from the one initially intended.
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38
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Abbarchi M, Cavigli L, Somaschini C, Bietti S, Gurioli M, Vinattieri A, Sanguinetti S. Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings. NANOSCALE RESEARCH LETTERS 2011; 6:569. [PMID: 22039893 PMCID: PMC3226682 DOI: 10.1186/1556-276x-6-569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/31/2011] [Indexed: 05/31/2023]
Abstract
A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications.
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Affiliation(s)
- Marco Abbarchi
- L.E.N.S. and Dipartimento di Fisica, Universitá di Firenze, Via Sansone 1, I-50019, Sesto Fiorentino, Italy
| | - Lucia Cavigli
- L.E.N.S. and Dipartimento di Fisica, Universitá di Firenze, Via Sansone 1, I-50019, Sesto Fiorentino, Italy
| | - Claudio Somaschini
- L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I-20125, Milano, Italy
| | - Sergio Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I-20125, Milano, Italy
| | - Massimo Gurioli
- L.E.N.S. and Dipartimento di Fisica, Universitá di Firenze, Via Sansone 1, I-50019, Sesto Fiorentino, Italy
| | - Anna Vinattieri
- L.E.N.S. and Dipartimento di Fisica, Universitá di Firenze, Via Sansone 1, I-50019, Sesto Fiorentino, Italy
| | - Stefano Sanguinetti
- L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I-20125, Milano, Italy
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39
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Jo M, Mano T, Sakoda K. Lasing in ultra-narrow emission from GaAs quantum dots coupled with a two-dimensional layer. NANOTECHNOLOGY 2011; 22:335201. [PMID: 21775803 DOI: 10.1088/0957-4484/22/33/335201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report electrically injected lasing in GaAs quantum dots (QDs) grown on GaAs(001) by droplet epitaxy. High-quality GaAs QDs with superior uniformity are formed using improved growth techniques involving the insertion of a two-dimensional layer, control of the As flux for GaAs crystallization, and thin AlGaAs layer capping with high-temperature annealing. The QDs show ultra-narrow luminescence with a linewidth of 20 meV. Ground-state lasing from a laser diode containing fivefold-stacked QD layers is observed at low temperature under pulsed operation.
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Affiliation(s)
- M Jo
- Quantum Dot Research Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
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40
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Somaschini C, Bietti S, Koguchi N, Sanguinetti S. Coupled quantum dot-ring structures by droplet epitaxy. NANOTECHNOLOGY 2011; 22:185602. [PMID: 21415467 DOI: 10.1088/0957-4484/22/18/185602] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The fabrication, by pure self-assembly, of GaAs/AlGaAs dot-ring quantum nanostructures is presented. The growth is performed via droplet epitaxy, which allows for the fine control, through As flux and substrate temperature, of the crystallization kinetics of nanometer scale metallic Ga reservoirs deposited on the surface. Such a procedure permits the combination of quantum dots and quantum rings into a single, multi-functional, complex quantum nanostructure.
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Affiliation(s)
- C Somaschini
- L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I-20125 Milano, Italy
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41
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Jo M, Duan G, Mano T, Sakoda K. Effects of low-temperature capping on the optical properties of GaAs/AlGaAs quantum wells. NANOSCALE RESEARCH LETTERS 2011; 6:76. [PMID: 21711596 PMCID: PMC3212224 DOI: 10.1186/1556-276x-6-76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 01/12/2011] [Indexed: 05/31/2023]
Abstract
We study the effects of low-temperature capping (200-450°C) on the optical properties of GaAs/AlGaAs quantum wells. Photoluminescence measurements clearly show the formation of abundant nonradiative recombination centers in an AlGaAs capping layer grown at 200°C, while there is a slight degradation of the optical quality in AlGaAs capping layers grown at temperatures above 350°C compared to that of a high-temperature capping layer. In addition, the optical quality can be restored by post-growth annealing without any structural change, except for the 200°C-capped sample.
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Affiliation(s)
- Masafumi Jo
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Guotao Duan
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Takaaki Mano
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Kazuaki Sakoda
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
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42
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Lee J. Instability of various configurations of in nano-crystals on GaAs (100) by droplet epitaxy. CrystEngComm 2011. [DOI: 10.1039/c0ce00768d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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43
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Liu Y, Gong Y, He L, Xie B, Chen X, Han M, Wang G. Formation of periodic nanoring arrays on self-assembled PS-b-PMMA film under rapid solvent-annealing. NANOSCALE 2010; 2:2065-2068. [PMID: 20820641 DOI: 10.1039/c0nr00207k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Periodic nanoring arrays are prepared by self-assembled poly styrene-block-polymethylmethacrylate (PS-b-PMMA) diblock copolymer under rapid solvent-annealing. The dimension of the nanorings can be modified by controlling the solvent-annealing time.
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Affiliation(s)
- Yuanjun Liu
- National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China
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44
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Bietti S, Somaschini C, Sarti E, Koguchi N, Sanguinetti S, Isella G, Chrastina D, Fedorov A. Photoluminescence Study of Low Thermal Budget III-V Nanostructures on Silicon by Droplet Epitaxy. NANOSCALE RESEARCH LETTERS 2010; 5:1650-1653. [PMID: 21076665 PMCID: PMC2956041 DOI: 10.1007/s11671-010-9689-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Accepted: 07/01/2010] [Indexed: 05/30/2023]
Abstract
We present of a detailed photoluminescence characterization of high efficiency GaAs/AlGaAs quantum nanostructures grown on silicon substrates. The whole process of formation of the GaAs/AlGaAs active layer was realized via droplet epitaxy and migration enhanced epitaxy maintaining the growth temperature ≤350°C, thus resulting in a low thermal budget procedure compatible with back-end integration of the fabricated materials on integrated circuits.
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Affiliation(s)
- S Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Via Cozzi 53, 20125, Milano, Italy
| | - C Somaschini
- L-NESS and Dipartimento di Scienza dei Materiali, Via Cozzi 53, 20125, Milano, Italy
| | - E Sarti
- L-NESS and Dipartimento di Scienza dei Materiali, Via Cozzi 53, 20125, Milano, Italy
| | - N Koguchi
- L-NESS and Dipartimento di Scienza dei Materiali, Via Cozzi 53, 20125, Milano, Italy
| | - S Sanguinetti
- L-NESS and Dipartimento di Scienza dei Materiali, Via Cozzi 53, 20125, Milano, Italy
| | - G Isella
- CNISM, L-NESS and Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100, Como, Italy
| | - D Chrastina
- CNISM, L-NESS and Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100, Como, Italy
| | - A Fedorov
- CNISM, L-NESS and Dipartimento di Fisica del Politecnico di Milano, Via Anzani 42, 22100, Como, Italy
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45
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Tersoff J, Jesson DE, Tang WX. Decomposition controlled by surface morphology during langmuir evaporation of GaAs. PHYSICAL REVIEW LETTERS 2010; 105:035702. [PMID: 20867779 DOI: 10.1103/physrevlett.105.035702] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Indexed: 05/29/2023]
Abstract
When GaAs is heated in vacuum, it decomposes into Ga and As as it evaporates. Real-time in situ surface electron microscopy reveals striking bursts of "daughter" droplet nucleation and growth when coalescence of large "parent" droplets exposes nonplanar surface regions. We analyze the behavior, predicting a morphology-dependent congruent evaporation temperature. Based on this we propose a new approach for the self-assembly and positioning of quantum structures via droplet epitaxy, which we demonstrate at the proof-of-concept level.
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Affiliation(s)
- J Tersoff
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
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46
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Wu J, Shao D, Dorogan VG, Li AZ, Li S, DeCuir EA, Manasreh MO, Wang ZM, Mazur YI, Salamo GJ. Intersublevel infrared photodetector with strain-free GaAs quantum dot pairs grown by high-temperature droplet epitaxy. NANO LETTERS 2010; 10:1512-1516. [PMID: 20356102 DOI: 10.1021/nl100217k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Normal incident photodetection at mid infrared spectral region is achieved using the intersublevel transitions from strain-free GaAs quantum dot pairs in Al(0.3)Ga(0.7)As matrix. The GaAs quantum dot pairs are fabricated by high temperature droplet epitaxy, through which zero strain quantum dot pairs are obtained from lattice matched materials. Photoluminescence, photoluminescence excitation optical spectroscopy, and visible-near-infrared photoconductivity measurement are carried out to study the electronic structure of the photodetector. Due to the intersublevel transitions from GaAs quantum dot pairs, a broadband photoresponse spectrum is observed from 3 to 8 microm with a full width at half-maximum of approximately 2.0 microm.
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Affiliation(s)
- Jiang Wu
- Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
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47
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Somaschini C, Bietti S, Sanguinetti S, Koguchi N, Fedorov A. Self-assembled GaAs/AlGaAs coupled quantum ring-disk structures by droplet epitaxy. NANOTECHNOLOGY 2010; 21:125601. [PMID: 20182013 DOI: 10.1088/0957-4484/21/12/125601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The fabrication, by droplet epitaxy, of a class of quantum nanostructures characterized by a regular, nanometres high, flat disks with a diameter of hundreds of nanometres and a hole at the centre encircled by a ring a few nanometres high, is presented here. A detailed analysis of the growth kinetics performed via in situ and ex situ probes allows us to propose a working model for the formation of these structures.
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Affiliation(s)
- C Somaschini
- L-NESS and Dipartimento di Scienza dei Materiali dell'Università degli Studi di Milano-Bicocca, Milano, Italy
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48
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Lee J, Wang Z, Hirono Y, Kim ES, Kim N, Park S, Wang C, Salamo GJ. Various configurations of In nanostructures on GaAs (100) by droplet epitaxy. CrystEngComm 2010. [DOI: 10.1039/c0ce00057d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Li X, Cao Y, Yang G. Thermodynamic theory of two-dimensional to three-dimensional growth transition in quantum dots self-assembly. Phys Chem Chem Phys 2010; 12:4768-72. [DOI: 10.1039/b927189a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Lee JH, Wang ZM, Kim ES, Kim NY, Park SH, Salamo GJ. Various Quantum- and Nano-Structures by III-V Droplet Epitaxy on GaAs Substrates. NANOSCALE RESEARCH LETTERS 2009; 5:308-14. [PMID: 20671787 PMCID: PMC2893769 DOI: 10.1007/s11671-009-9481-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 10/28/2009] [Indexed: 05/29/2023]
Abstract
We report on various self-assembled In(Ga)As nanostructures by droplet epitaxy on GaAs substrates using molecular beam epitaxy. Depending on the growth condition and index of surfaces, various nanostructures can be fabricated: quantum dots (QDs), ring-like and holed-triangular nanostructures. At near room temperatures, by limiting surface diffusion of adatoms, the size of In droplets suitable for quantum confinement can be fabricated and thus InAs QDs are demonstrated on GaAs (100) surface. On the other hand, at relatively higher substrate temperatures, by enhancing the surface migrations of In adatoms, super lower density of InGaAs ring-shaped nanostructures can be fabricated on GaAs (100). Under an identical growth condition, holed-triangular InGaAs nanostructures can be fabricated on GaAs type-A surfaces, while ring-shaped nanostructures are formed on GaAs (100). The formation mechanism of various nanostructures can be understood in terms of intermixing, surface diffusion, and surface reconstruction.
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Affiliation(s)
- JH Lee
- Department of Electronic Engineering, Kwangwoon University, Nowon-gu Seoul, 139-701, South Korea
| | - Zh M Wang
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - ES Kim
- Department of Electronic Engineering, Kwangwoon University, Nowon-gu Seoul, 139-701, South Korea
| | - NY Kim
- Department of Electronic Engineering, Kwangwoon University, Nowon-gu Seoul, 139-701, South Korea
| | - SH Park
- Department of Electronic Engineering, Kwangwoon University, Nowon-gu Seoul, 139-701, South Korea
| | - GJ Salamo
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
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