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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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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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Abbarchi M, Mano T, Kuroda T, Sakoda K. Exciton Dynamics in Droplet Epitaxial Quantum Dots Grown on (311)A-Oriented Substrates. NANOMATERIALS 2020; 10:nano10091833. [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
- Correspondence:
| | - 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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Zhao TM, Chen Y, Yu Y, Li Q, Davanco M, Liu J. Advanced technologies for quantum photonic devices based on epitaxial quantum dots. ADVANCED QUANTUM TECHNOLOGIES 2020; 3:10.1002/qute.201900034. [PMID: 36452403 PMCID: PMC9706462 DOI: 10.1002/qute.201900034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Indexed: 05/12/2023]
Abstract
Quantum photonic devices are candidates for realizing practical quantum computers and networks. The development of integrated quantum photonic devices can greatly benefit from the ability to incorporate different types of materials with complementary, superior optical or electrical properties on a single chip. Semiconductor quantum dots (QDs) serve as a core element in the emerging modern photonic quantum technologies by allowing on-demand generation of single-photons and entangled photon pairs. During each excitation cycle, there is one and only one emitted photon or photon pair. QD photonic devices are on the verge of unfolding for advanced quantum technology applications. In this review, we focus on the latest significant progress of QD photonic devices. We first discuss advanced technologies in QD growth, with special attention to droplet epitaxy and site-controlled QDs. Then we overview the wavelength engineering of QDs via strain tuning and quantum frequency conversion techniques. We extend our discussion to advanced optical excitation techniques recently developed for achieving the desired emission properties of QDs. Finally, the advances in heterogeneous integration of active quantum light-emitting devices and passive integrated photonic circuits are reviewed, in the context of realizing scalable quantum information processing chips.
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Affiliation(s)
- Tian Ming Zhao
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Yan Chen
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany
| | - Ying Yu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Qing Li
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Marcelo Davanco
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
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Balakirev SV, Solodovnik MS, Eremenko MM, Konoplev BG, Ageev OA. Mechanism of nucleation and critical layer formation during In/GaAs droplet epitaxy. NANOTECHNOLOGY 2019; 30:505601. [PMID: 31480037 DOI: 10.1088/1361-6528/ab40d6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fabrication of AIIIBV nanostructures by droplet epitaxy has many advantages over other epitaxial techniques. Although various characteristics of the growth by droplet epitaxy have been thoroughly studied for both lattice-matched and mismatched systems, little is known about physical processes hindering the formation of small size InAs/GaAs nanostructure arrays with low density and thin wetting layer. In this paper, we experimentally demonstrate that the indium droplet diameter can be reduced by decreasing the deposition time, but this reduction is limited by a critical thickness of droplet formation dependent on the substrate temperature. Using the kinetic Monte Carlo model, we propose a mechanism considering that the droplet formation begins when the system overcomes a barrier determined by the substrate attraction. As a result of physical and chemical balancing between adatom aggregation and substrate wetting, this attraction becomes weaker with increasing either temperature or deposition amount, which leads to the critical layer formation and subsequent nucleation. Using this mechanism, it is possible to provide a wide control over the nanostructure growth which is especially important at high temperatures when the processes of the island ripening are particularly intensive.
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Affiliation(s)
- Sergey V Balakirev
- Department of Nanotechnologies and Microsystems, Southern Federal University, Institute of Nanotechnologies, Electronics and Equipment Engineering, 2 Shevchenko St., Taganrog 347922, Russia
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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: 51] [Impact Index Per Article: 10.2] [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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Bietti S, Basset FB, Scarpellini D, Fedorov A, Ballabio A, Esposito L, Elborg M, Kuroda T, Nemcsics Á, Tóth L, Manzoni C, Vozzi C, Sanguinetti S. Ga metal nanoparticle-GaAs quantum molecule complexes for terahertz generation. NANOTECHNOLOGY 2018; 29:365602. [PMID: 29911655 DOI: 10.1088/1361-6528/aacd20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A hybrid metal-semiconductor nanosystem for the generation of THz radiation, based on the fabrication of GaAs quantum molecules-Ga metal nanoparticles complexes through a self assembly approach, is proposed. The role of the growth parameters, the substrate temperature, the Ga and As flux during the quantum dot molecule (QDM) fabrication and the metal nanoparticle alignment are discussed. The tuning of the relative positioning of QDMs and metal nanoparticles is obtained through the careful control of Ga droplet nucleation sites via Ga surface diffusion. The electronic structure of a typical QDM was evaluated on the base of the morphological characterizations performed by atomic force microscopy and cross sectional scanning electron microscopy, and the predicted results confirmed by micro-photoluminescence experiments, showing that the Ga metal nanoparticle-GaAs quantum molecule complexes are suitable for terahertz generation from intraband transition.
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Affiliation(s)
- Sergio Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 53, I-20125 Milano, Italy
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Choi I, Lee H, Lee CR, Jeong KU, Kim JS. Formation of spherical-shaped GaN and InN quantum dots on curved SiN/Si surface. NANOTECHNOLOGY 2018; 29:315603. [PMID: 29749963 DOI: 10.1088/1361-6528/aac414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This paper reports the formation of GaN and InN quantum dots (QDs) with symmetric spherical shapes, grown on SiN/Si(111). Spherical QDs are grown by modulating initial growth behavior via gallium and indium droplets functioning as nucleation sites for QDs. Field-emission scanning electron microscope (FE-SEM) images show that GaN and InN QDs are formed on curved SiN/Si(111) instead of on a flat surface similar to balls on a latex mattress. This is considerably different from the structural properties of In(Ga)As QDs grown on GaAs or InP. In addition, considering the shape of the other III-V semiconductor QDs, the QDs in this study are very close to the ideal shape of zero-dimensional nanostructures. Transmission-electron microscope images show the formation of symmetric GaN and InN QDs with a round shape, agreeing well with the FE-SEM results. Compared to other III-V semiconductor QDs, the unique structural properties of Si-based GaN and InN QDs are strongly related to the modulation in the initial nucleation characteristics due to the presence of droplets, the degree of lattice mismatch between GaN or InN and SiN/Si(111), and the melt-back etching phenomenon.
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Affiliation(s)
- Ilgyu Choi
- Department of Electronic and Information Materials Engineering, Division of Advanced Materials Engineering, and Research Center of Advanced Materials Development (RCAMD), Chonbuk National University, Jeonju 54896, Republic of Korea
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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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10
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Basso Basset F, Bietti S, Reindl M, Esposito L, Fedorov A, Huber D, Rastelli A, Bonera E, Trotta R, Sanguinetti S. High-Yield Fabrication of Entangled Photon Emitters for Hybrid Quantum Networking Using High-Temperature Droplet Epitaxy. NANO LETTERS 2018; 18:505-512. [PMID: 29239186 DOI: 10.1021/acs.nanolett.7b04472] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Several semiconductor quantum dot techniques have been investigated for the generation of entangled photon pairs. Among the other techniques, droplet epitaxy enables the control of the shape, size, density, and emission wavelength of the quantum emitters. However, the fraction of the entanglement-ready quantum dots that can be fabricated with this method is still limited to around 5%, and matching the energy of the entangled photons to atomic transitions (a promising route toward quantum networking) remains an outstanding challenge. Here, we overcome these obstacles by introducing a modified approach to droplet epitaxy on a high symmetry (111)A substrate, where the fundamental crystallization step is performed at a significantly higher temperature as compared with previous reports. Our method drastically improves the yield of entanglement-ready photon sources near the emission wavelength of interest, which can be as high as 95% due to the low values of fine structure splitting and radiative lifetime, together with the reduced exciton dephasing offered by the choice of GaAs/AlGaAs materials. The quantum dots are designed to emit in the operating spectral region of Rb-based slow-light media, providing a viable technology for quantum repeater stations.
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Affiliation(s)
- Francesco Basso Basset
- L-NESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University , Altenbergerstraße 69, Linz 4040, Austria
| | - Sergio Bietti
- L-NESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
| | - Marcus Reindl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University , Altenbergerstraße 69, Linz 4040, Austria
| | - Luca Esposito
- L-NESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
| | | | - Daniel Huber
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University , Altenbergerstraße 69, Linz 4040, Austria
| | - Armando Rastelli
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University , Altenbergerstraße 69, Linz 4040, Austria
| | - Emiliano Bonera
- L-NESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
| | - Rinaldo Trotta
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University , Altenbergerstraße 69, Linz 4040, Austria
| | - Stefano Sanguinetti
- L-NESS and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
- L-NESS and CNR-IFN , via Anzani 42, I-22100 Como, Italy
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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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Li MY, Sui M, Kim ES, Lee J. Effect of Au thickness on the evolution of self-assembled Au droplets on GaAs (111)A and (100). NANOSCALE RESEARCH LETTERS 2014; 9:407. [PMID: 25170335 PMCID: PMC4141912 DOI: 10.1186/1556-276x-9-407] [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: 07/17/2014] [Accepted: 08/14/2014] [Indexed: 06/03/2023]
Abstract
In this paper, we report the effect of Au thickness on the self-assembled Au droplets on GaAs (111)A and (100). The evolution of Au droplets on GaAs (111)A and (100) with the increased Au thickness progress in the Volmer-Weber growth mode results in distinctive 3-D islands. Under an identical growth condition, depending on the thickness of Au deposition, the self-assembled Au droplets show different size and density distributions, while the average height is increased by approximately 420% and the diameter is increased by approximately 830%, indicating a preferential lateral expansion. Au droplets show an opposite evolution trend: the increased size along with the decreased density as a function of the Au thickness. Also, the density shifts on the orders of over two magnitude between 4.23 × 10(10) and 1.16 × 10(8) cm(-2) over the thickness range tested. At relatively thinner thicknesses below 4 nm, the self-assembled Au droplets sensitively respond to the thickness variation, evidenced by the sharper slopes of dimensions and density plots. The results are systematically analyzed and discussed in terms of atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), cross-sectional surface line profiles, and Fourier filter transform (FFT) power spectra.
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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
| | - 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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13
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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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Abbarchi M, Kuroda T, Duval R, Mano T, Sakoda K. Scanning Fabry-Pérot interferometer with largely tuneable free spectral range for high resolution spectroscopy of single quantum dots. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:073103. [PMID: 21806168 DOI: 10.1063/1.3601016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on the implementation of a scanning Fabry-Pérot interferometer for photoluminescence spectroscopy investigation. We choose a conveniently small reflectivity of the two planar semitransparent mirrors which, in spite of a moderate cavity finesse, ensures a good mechanical stability over a long time. We also exploit the large tuneability of the cavity length (i.e., of the free spectral range) for changing the spectral resolution over two order of magnitude (from ~300 μeV to ~4 μeV in full width at half maximum). Such a characteristic easily allows to scan both sharp and broad luminescence bands. We test our Fabry-Pérot interferometer on sharp photoluminescence lines resulting from excitonic recombination in self-assembled GaAs quantum dots. We demonstrate the ability of our system to resolve linewidth as small as 4 μeV.
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Affiliation(s)
- Marco Abbarchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
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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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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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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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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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