1
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Zhang Y, Wang B, Miao C, Chai H, Hong W, Ross FM, Wen RT. Controlled formation of three-dimensional cavities during lateral epitaxial growth. Nat Commun 2024; 15:2247. [PMID: 38472172 DOI: 10.1038/s41467-024-46222-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Epitaxial growth is a fundamental step required to create devices for the semiconductor industry, enabling different materials to be combined in layers with precise control of strain and defect structure. Patterning the growth substrate with a mask before performing epitaxial growth offers additional degrees of freedom to engineer the structure and hence function of the semiconductor device. Here, we demonstrate that conditions exist where such epitaxial lateral overgrowth can produce complex, three-dimensional structures that incorporate cavities of deterministic size. We grow germanium on silicon substrates patterned with a dielectric mask and show that fully-enclosed cavities can be created through an unexpected self-assembly process that is controlled by surface diffusion and surface energy minimization. The result is confined cavities enclosed by single crystalline Ge, with size and position tunable through the initial mask pattern. We present a model to account for the observed cavity symmetry, pinch-off and subsequent evolution, reflecting the dominant role of surface energy. Since dielectric mask patterning and epitaxial growth are compatible with conventional device processing steps, we suggest that this mechanism provides a strategy for developing electronic and photonic functionalities.
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Affiliation(s)
- Yiwen Zhang
- Department of Materials Science and Engineering, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Baoming Wang
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Changxu Miao
- Shenzhen Key Laboratory of Soft Mechanics and Smart Manufacturing, Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Haozhi Chai
- Department of Materials Science and Engineering, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China
| | - Wei Hong
- Shenzhen Key Laboratory of Soft Mechanics and Smart Manufacturing, Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China.
| | - Frances M Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Rui-Tao Wen
- Department of Materials Science and Engineering, Southern University of Science and Technology, 518055, Shenzhen, Guangdong, China.
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2
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Horn-von Hoegen M. Structural dynamics at surfaces by ultrafast reflection high-energy electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:021301. [PMID: 38495951 PMCID: PMC10942804 DOI: 10.1063/4.0000234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/13/2024] [Indexed: 03/19/2024]
Abstract
Many fundamental processes of structural changes at surfaces occur on a pico- or femtosecond timescale. In order to study such ultrafast processes, we have combined modern surface science techniques with fs-laser pulses in a pump-probe scheme. Grazing incidence of the electrons ensures surface sensitivity in ultrafast reflection high-energy electron diffraction (URHEED). Utilizing the Debye-Waller effect, we studied the nanoscale heat transport from an ultrathin film through a hetero-interface or the damping of vibrational excitations in monolayer adsorbate systems on the lower ps-timescale. By means of spot profile analysis, the different cooling rates of epitaxial Ge nanostructures of different size and strain state were determined. The excitation and relaxation dynamics of a driven phase transition far away from thermal equilibrium is demonstrated using the In-induced (8 × 2) reconstruction on Si(111). This Peierls-distorted surface charge density wave system exhibits a discontinuous phase transition of first order at 130 K from a (8 × 2) insulating ground state to (4 × 1) metallic excited state. Upon excitation by a fs-laser pulse, this structural phase transition is non-thermally driven in only 700 fs into the excited state. A small barrier of 40 meV hinders the immediate recovery of the ground state, and the system is found in a metastable supercooled state for up to few nanoseconds.
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Affiliation(s)
- Michael Horn-von Hoegen
- Department of Physics and Center for Nanointegration CENIDE, University of Duisburg-Essen, Lotharstrasse. 1, 47057 Duisburg, Germany
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3
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Yan J, Zhang Z, Zhang N, Huang Q, Zhan Y, Jiang Z, Zhong Z. Competitive Growth of Ge Quantum Dots on a Si Micropillar with Pits for a Precisely Site-Controlled QDs/Microdisk System. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2323. [PMID: 37630907 PMCID: PMC10458077 DOI: 10.3390/nano13162323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023]
Abstract
Semiconductor quantum dots (QDs)/microdisks promise a unique system for comprehensive studies on cavity quantum electrodynamics and great potential for on-chip integrated light sources. Here, we report on a strategy for precisely site-controlled Ge QDs in SiGe microdisks via self-assembly growth of QDs on a micropillar with deterministic pits and subsequent etching. The competitive growth of QDs in pits and at the periphery of the micropillar is disclosed. By adjusting the growth temperature and Ge deposition, as well as the pit profiles, QDs can exclusively grow in pits that are exactly located at the field antinodes of the corresponding cavity mode of the microdisk. The inherent mechanism of the mandatory addressability of QDs is revealed in terms of growth kinetics based on the non-uniform surface chemical potential around the top of the micropillar with pits. Our results demonstrate a promising approach to scalable and deterministic QDs/microdisks with strong light-matter interaction desired for fundamental research and technological applications.
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Affiliation(s)
- Jia Yan
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
| | - Zhifang Zhang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
| | - Ningning Zhang
- Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Xidian University, Xi’an 710071, China
| | - Qiang Huang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
| | - Yan Zhan
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
| | - Zuimin Jiang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
| | - Zhenyang Zhong
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, China
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4
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Shu Q, Huang P, Yang F, Yang L, Chen L. Study on crystal growth of Ge/Si quantum dots at different Ge deposition by using magnetron sputtering technique. Sci Rep 2023; 13:7511. [PMID: 37161032 PMCID: PMC10169779 DOI: 10.1038/s41598-023-34284-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/27/2023] [Indexed: 05/11/2023] Open
Abstract
We investigated the growth and evolution of Si-based Ge quantum dots (Ge/Si QDs) under low Ge deposition (1.2-4.4 nm thick) using magnetron sputtering. The morphology and structure of QDs were analyzed with the help of an atomic force microscope (AFM), scanning electron microscope, transmission electron microscope, Raman, surface energy theory and dynamics theory, the photoelectric properties of QDs were characterized by photoluminescence (PL) spectra. The results showed that the growth mechanism of QDs conformed to Stranski-Krastanow mode, but the typical thickness of the wetting layer was nearly three times higher than those derived from conventional technologies such as molecular beam epitaxy, chemical vapor deposition, solid phase epitaxy and so on. Meanwhile, the shape evolution of QDs was very different from existing reports. The specific internal causes of these novel phenomena were analyzed and confirmed and reported in this paper. In addition, the AFM, Raman, and PL tests all indicated that the QDs grown when 3.4 nm Ge was deposited have the most excellent morphology, structure, and optoelectronic performance. Our work lays a foundation for further exploration of the controllable growth of QDs at high deposition rates, which is a new way to realize the industrialization of QDs used for future devices.
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Affiliation(s)
- Qijiang Shu
- Institute of Information, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Pengru Huang
- School of Material Science and Engineering, Guangxi Key Laboratory of Information Materials and Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, Guilin University of Electronic Technology, Guilin, 541004, China
| | - Fuhua Yang
- Institute of Information, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Linjing Yang
- Institute of Information, Yunnan University of Chinese Medicine, Kunming, 650500, China
| | - Lei Chen
- College of Chinese Materia Medica, Yunnan University of Chinese Medicine, Kunming, 650500, China.
- Faculty of Narcotics Control, Yunnan Police College, Kunming, 650223, China.
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5
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Minenkov A, Šantić N, Truglas T, Aberl J, Vukušić L, Brehm M, Groiss H. Advanced preparation of plan-view specimens on a MEMS chip for in situ TEM heating experiments. MRS BULLETIN 2022; 47:359-370. [PMID: 35968543 PMCID: PMC9365753 DOI: 10.1557/s43577-021-00255-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 12/03/2021] [Indexed: 06/15/2023]
Abstract
UNLABELLED In situ transmission electron microscopy (TEM) is a powerful tool for advanced material characterization. It allows real-time observation of structural evolution at the atomic level while applying different stimuli such as heat. However, the validity of analysis strongly depends on the quality of the specimen, which has to be prepared by thinning the bulk material to electron transparency while maintaining the pristine properties. To address this challenge, a novel method of TEM samples preparation in plan-view geometry was elaborated based on the combination of the wedge polishing technique and an enhanced focused ion beam (FIB) workflow. It involves primary mechanical thinning of a broad sample area from the backside followed by FIB-assisted installation on the MEMS-based sample carrier. The complete step-by-step guide is provided, and the method's concept is discussed in detail making it easy to follow and adapt for diverse equipment. The presented approach opens the world of in situ TEM heating experiments for a vast variety of fragile materials. The principle and significant advantage of the proposed method are demonstrated by new insights into the stability and thermal-induced strain relaxation of Ge Stranski-Krastanov islands on Si during in situ TEM heating. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1557/s43577-021-00255-5.
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Affiliation(s)
- Alexey Minenkov
- Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Natalija Šantić
- Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Tia Truglas
- Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
- Tietz Video and Image Processing Systems GmbH, Eremitenweg 1, 82131 Gauting, Germany
| | - Johannes Aberl
- Institute of Semiconductor and Solid-State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Lada Vukušić
- Institute of Semiconductor and Solid-State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Moritz Brehm
- Institute of Semiconductor and Solid-State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Heiko Groiss
- Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
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6
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Jung C, Ihm Y, Cho DH, Lee H, Nam D, Kim S, Eom IT, Park J, Kim C, Kim Y, Fan J, Ji N, Morris JR, Owada S, Tono K, Shim JH, Jiang H, Yabashi M, Ishikawa T, Noh DY, Song C. Inducing thermodynamically blocked atomic ordering via strongly driven nonequilibrium kinetics. SCIENCE ADVANCES 2021; 7:eabj8552. [PMID: 34936432 PMCID: PMC8694629 DOI: 10.1126/sciadv.abj8552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 11/02/2021] [Indexed: 05/22/2023]
Abstract
Ultrafast light-matter interactions enable inducing exotic material phases by promoting access to kinetic processes blocked in equilibrium. Despite potential opportunities, actively using nonequilibrium kinetics for material discovery is limited by the poor understanding on intermediate states of driven systems. Here, using single-pulse time-resolved imaging with x-ray free-electron lasers, we found intermediate states of photoexcited bismuth nanoparticles that showed kinetically reversed surface ordering during ultrafast melting. This entropy-lowering reaction was further investigated by molecular dynamics simulations to reveal that observed kinetics were thermodynamically buried in equilibrium, which emphasized the critical role of electron-mediated ultrafast free-energy modification in inducing exotic material phases. This study demonstrated that ultrafast photoexcitations of electrons provide an efficient strategy to induce hidden material phases by overcoming thermodynamic barriers via nonequilibrium reaction pathways.
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Affiliation(s)
- Chulho Jung
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Yungok Ihm
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Do Hyung Cho
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Heemin Lee
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
| | - Daewoong Nam
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - Sangsoo Kim
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - In-Tae Eom
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Pohang Accelerator Laboratory, Pohang 37673, Korea
| | - Jaehyun Park
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Chan Kim
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- European XFEL GmbH, Schenefeld 22869, Germany
| | - Yoonhee Kim
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- European XFEL GmbH, Schenefeld 22869, Germany
| | - Jiadong Fan
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - Nianjing Ji
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - James R. Morris
- Materials Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Ames Laboratory, Iowa State University, Ames, IA 50011, USA
| | - Shigeki Owada
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Ji Hoon Shim
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Department of Chemistry, POSTECH, Pohang 37673, Korea
| | - Huaidong Jiang
- School of Physical Sciences, ShanghaiTech University, Shanghai, China
| | - Makina Yabashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | | | - Do Young Noh
- Department of Physics and Photon Science and School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
- Institute for Basic Sciences (IBS), Daejeon 34126, Korea
| | - Changyong Song
- Department of Physics, POSTECH, Pohang 37673, Korea
- Photon Science Center, POSTECH, Pohang 37673, Korea
- Asia Pacific Center for Theoretical Physics, POSTECH, Pohang 37673, Korea
- Corresponding author.
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7
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Schuster J, Aberl J, Vukušić L, Spindlberger L, Groiss H, Fromherz T, Brehm M, Schäffler F. Photoluminescence enhancement by deterministically site-controlled, vertically stacked SiGe quantum dots. Sci Rep 2021; 11:20597. [PMID: 34663889 PMCID: PMC8523567 DOI: 10.1038/s41598-021-99966-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/05/2021] [Indexed: 11/09/2022] Open
Abstract
The Si/SiGe heterosystem would be ideally suited for the realization of complementary metal-oxide-semiconductor (CMOS)-compatible integrated light sources, but the indirect band gap, exacerbated by a type-II band offset, makes it challenging to achieve efficient light emission. We address this problem by strain engineering in ordered arrays of vertically close-stacked SiGe quantum dot (QD) pairs. The strain induced by the respective lower QD creates a preferential nucleation site for the upper one and strains the upper QD as well as the Si cap above it. Electrons are confined in the strain pockets in the Si cap, which leads to an enhanced wave function overlap with the heavy holes near the upper QD’s apex. With a thickness of the Si spacer between the stacked QDs below 5 nm, we separated the functions of the two QDs: The role of the lower one is that of a pure stressor, whereas only the upper QD facilitates radiative recombination of QD-bound excitons. We report on the design and strain engineering of the QD pairs via strain-dependent Schrödinger-Poisson simulations, their implementation by molecular beam epitaxy, and a comprehensive study of their structural and optical properties in comparison with those of single-layer SiGe QD arrays. We find that the double QD arrangement shifts the thermal quenching of the photoluminescence signal at higher temperatures. Moreover, detrimental light emission from the QD-related wetting layers is suppressed in the double-QD configuration.
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Affiliation(s)
- Jeffrey Schuster
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria.
| | - Johannes Aberl
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Lada Vukušić
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Lukas Spindlberger
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Heiko Groiss
- Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Thomas Fromherz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Moritz Brehm
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
| | - Friedrich Schäffler
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria
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8
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Ghosh P, Gupta N, Dhankhar M, Ranganathan M. Kinetic Monte Carlo simulations of self-organization of Ge islands on Si(001). Phys Chem Chem Phys 2021; 23:19022-19031. [PMID: 34612440 DOI: 10.1039/d1cp00069a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-organization of germanium islands on a silicon(001) substrate is studied using lattice-based kinetic Monte Carlo simulations. These islands form spontaneously via the Stranski-Krastanov mode during growth. The interplay of deposition flux and competing surface diffusion leads to a size and shape distribution of islands that varies with temperature and coverage. For the simulation parameters chosen, a kinetic regime of irreversible growth is observed at 500 K, and this changes to quasi-equilibrium growth at 600 K. At 550 K, we see that the surface roughness increases abruptly from a low value and crosses the roughness curve at 600 K. This behavior is explained on the basis of a change in the island formation mechanism. At 500 K, the island formation involves a nucleation barrier; whereas at 600 K this barrier is almost nonexistent. At an intermediate temperature, the stochastic effects due to the incoming flux initially slow down island growth, but the subsequent island nucleation rapidly increases the roughness. These results illustrate how island self-assembly is affected by mechanistic in addition to kinetic and energetic effects. Our results are discussed in the context of experiments on a Si-Ge system and show how the kMC models can be used to understand the processes in heteroepitaxial growth.
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Affiliation(s)
- Paramita Ghosh
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India.
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9
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Dey AB, Sanyal MK, Patil S, Ali K, Biswas D, Thakur S, Maiti K. Local excitons in Si/Ge inverted quantum huts (IQHs) embedded Si. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:42LT01. [PMID: 34311451 DOI: 10.1088/1361-648x/ac17b0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
We investigate the properties of excitons in the SiGe inverted quantum huts (IQHs) embedded in Si employing high-resolution x-ray photoemission spectroscopy. Ultra-small Si/Ge IQHs (13.3 nm × 6.6 nm) were grown on a Si buffer layer deposited on a Si (001) substrate using molecular beam epitaxy. We study the behavior of the excitons at different depths of the IQH structures by exposing the desired surfaces via controlled sputtering and annealing processes. The Si and Ge core level spectra show interesting properties at different surfaces; additionally, we discover distinct new features at the lower binding energy side of the Ge 3dpeak. The emergence of these features is attributed to the final state effects arising from core hole screening by the excitons. The properties of these features in the spectra collected at different locations of the IQHs are found significantly different from each other, indicating the local character of the excitons. These results provide a pathway to study the properties of excitons in such quantum structures. The evidence of the local character of the excitons suggests a type I behavior of the system, which is important for the devices for optoelectronic applications, quantum communications, etc.
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Affiliation(s)
- Arka Bikash Dey
- Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India
| | - Milan K Sanyal
- Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India
| | - Swapnil Patil
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Khadiza Ali
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Deepnarayan Biswas
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Sangeeta Thakur
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Kalobaran Maiti
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005, India
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10
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Unusual layer-by-layer growth of epitaxial oxide islands during Cu oxidation. Nat Commun 2021; 12:2781. [PMID: 33986274 PMCID: PMC8119701 DOI: 10.1038/s41467-021-23043-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 03/31/2021] [Indexed: 02/03/2023] Open
Abstract
Elucidating metal oxide growth mechanisms is essential for precisely designing and fabricating nanostructured oxides with broad applications in energy and electronics. However, current epitaxial oxide growth methods are based on macroscopic empirical knowledge, lacking fundamental guidance at the nanoscale. Using correlated in situ environmental transmission electron microscopy, statistically-validated quantitative analysis, and density functional theory calculations, we show epitaxial Cu2O nano-island growth on Cu is layer-by-layer along Cu2O(110) planes, regardless of substrate orientation, contradicting classical models that predict multi-layer growth parallel to substrate surfaces. Growth kinetics show cubic relationships with time, indicating individual oxide monolayers follow Frank-van der Merwe growth whereas oxide islands follow Stranski-Krastanov growth. Cu sources for island growth transition from step edges to bulk substrates during oxidation, contrasting with classical corrosion theories which assume subsurface sources predominate. Our results resolve alternative epitaxial island growth mechanisms, improving the understanding of oxidation dynamics critical for advanced manufacturing at the nanoscale.
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11
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Banerjee P, Roy C, Jiménez JJ, Morales FM, Bhattacharyya S. Atomically resolved 3D structural reconstruction of small quantum dots. NANOSCALE 2021; 13:7550-7557. [PMID: 33928976 DOI: 10.1039/d1nr00466b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Semiconducting quantum dots (QDs) have potential applications in light-emitting diodes, single-photon sources and quantum computing due to shape-dependent (opto) electronic properties. Atomic resolution 3D-structure determination is important in understanding growth kinetics and improving device performance. 3D-reconstruction of large QDs was reported using characterization techniques like atomic force microscopy, atom probe tomography and tilt series electron tomography, but, still, atomic resolution tomography of QDs, especially those sized below 10 nm, is a challenge. Inline-3D-holography is an emerging and promising technique to perform atomic resolution tomography at low electron doses. In the present study, atomically resolved 3D structures of QDs were reconstructed using inline-3D-holography, implemented on InN QDs (<10 nm) grown on a Si substrate. The residual amorphous glue distorts the exit surface geometry; hence an error correction method was proposed. This is the first experimental evidence of pre-pyramid shaped 3D structure of QDs sized below 10 nm that supports theoretical predictions.
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Affiliation(s)
- Pritam Banerjee
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Chiranjit Roy
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Juan Jesús Jiménez
- IMEYMAT: Institute of Research on Electron Microscopy and Materials, University of Cádiz, Spain and Department of Materials Science and Metallurgic Engineering, and Inorganic Chemistry, Faculty of Sciences, University of Cádiz, Puerto Real, 11510 Cádiz, Spain
| | - Francisco Miguel Morales
- IMEYMAT: Institute of Research on Electron Microscopy and Materials, University of Cádiz, Spain and Department of Materials Science and Metallurgic Engineering, and Inorganic Chemistry, Faculty of Sciences, University of Cádiz, Puerto Real, 11510 Cádiz, Spain
| | - Somnath Bhattacharyya
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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12
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Tuktamyshev A, Fedorov A, Bietti S, Vichi S, Tambone R, Tsukamoto S, Sanguinetti S. Nucleation of Ga droplets self-assembly on GaAs(111)A substrates. Sci Rep 2021; 11:6833. [PMID: 33767304 PMCID: PMC7994575 DOI: 10.1038/s41598-021-86339-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/15/2021] [Indexed: 11/10/2022] Open
Abstract
We investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around \documentclass[12pt]{minimal}
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\begin{document}$$350\,^{\circ }\hbox {C}$$\end{document}350∘C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.
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Affiliation(s)
- Artur Tuktamyshev
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy. .,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy.
| | - Alexey Fedorov
- CNR Istituto di Fotonica e Nanotecnologie, Piazza Leonardo da Vinci 32, 20133, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Sergio Bietti
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Stefano Vichi
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Riccardo Tambone
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Shiro Tsukamoto
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
| | - Stefano Sanguinetti
- Department of Material Science, University of Milano-Bicocca, via R. Cozzi 55, 20125, Milan, Italy.,Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Polo di Como, via F. Anzani 42, 22100, Como, Italy
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13
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Silva CD, Corradini PG, Del Colle V, Mascaro LH, de Lima FHB, Pereira EC. Pt/Rh/Pt and Pt/Ru/Pt multilayers for the electrochemical oxidation of methanol and ethanol. Electrochim Acta 2020. [DOI: 10.1016/j.electacta.2020.136674] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Computational Analysis of Low-Energy Dislocation Configurations in Graded Layers. CRYSTALS 2020. [DOI: 10.3390/cryst10080661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Graded layers are widely exploited in semiconductor epitaxy as they typically display lower threading dislocation density with respect to constant-composition layers. However, strain relaxation occurs via a rather complex distribution of misfit dislocations. Here we exploit a suitable computational approach to investigate dislocation distributions minimizing the elastic energy in overcritical constant-composition and graded layers. Predictions are made for SiGe/Si systems, but the methodology, based on the exact (albeit in two dimensions and within linear elasticity theory) solution of the stress field associated with a periodic distribution of defects, is general. Results are critically compared with experiments, when possible, and with a previous mean-field model. A progressive transition from one-dimensional to two-dimensional distributions of defects when continuous linear grading is approached is clearly observed. Interestingly, analysis of the low-energy distribution of dislocations reveals close analogies with typical pile-ups as produced by dislocation multiplication.
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15
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Zhang N, Chen P, Peng K, Zhang L, Liu T, Yan J, Jiang Z, Zhong Z. Promising modulation of self-assembled Ge-rich QDs by ultra-heavy phosphorus doping. NANOSCALE 2020; 12:13137-13144. [PMID: 32584338 DOI: 10.1039/d0nr00411a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Self-assembled Ge-rich quantum dots (QDs) can not only act as a prototype model for the fundamental studies of heteroepitaxial growth but also have great potential in optoelectronic devices for telecommunication and monolithic optical-electronic integrated circuits. Here, we report the unique features of Ge-rich QDs ultra-heavily doped with phosphorus (P) and embedded in a thin SiGe alloy film on Si (001) substrates. The ultra-heavy P doping considerably reduces the size of Ge-rich QDs and improves their uniformity. The inherent mechanism is associated with the reductions of both surface energy and the diffusion length of adatoms during QD growth promoted by the P dopants. Raman spectra indicate that the Ge content and strain in QDs are essentially not modified by the P doping. Particularly, the power- and temperature-dependent photoluminescence (PL) spectra demonstrate a type-I band alignment of Ge-rich QDs/SiGe alloy film due to the ultra-heavy P doping, which gives rise to additional low energy levels of electrons in QDs. Moreover, the PL of Ge-rich QDs is remarkably enhanced by ultra-heavy P doping at temperatures over 80 K. Over 3 times enhancement is obtained at 245 K. These results indicate that the overall quantum efficiency of Ge-rich QDs is substantially improved by the ultra-heavy P doping, which facilitates the applications of Ge-rich QDs in Si-based innovative optoelectronic devices.
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Affiliation(s)
- Ningning Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China.
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16
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Singh S, Katiyar AK, Sarkar A, Shihabudeen PK, Chaudhuri AR, Goswami DK, Ray SK. Superior optical (λ ∼ 1550 nm) emission and detection characteristics of Ge microdisks grown on virtual Si 0.5Ge 0.5/Si substrates using molecular beam epitaxy. NANOTECHNOLOGY 2020; 31:115206. [PMID: 31756729 DOI: 10.1088/1361-6528/ab5abe] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the optical characteristics of relatively large sized (∼7.0-8.0 μm) but low aspect ratio Ge microdisks grown on a virtual Si0.5Ge0.5 substrate using molecular beam epitaxy following the Stranski-Krastanov growth mechanism. Grown microdisks with very low aspect ratio Ge islands exhibit direct band gap (∼0.8 eV) photoluminescence emission sustainable up to room temperature, enabled by the confinement of carriers into the microdisks. p-i-n diodes with an intrinsic layer containing Ge microdisks have been fabricated to study their emission and photoresponse characteristics at an optical communication wavelength of ∼1550 nm. A strong electroluminescence at 1550 nm has been achieved at low temperatures in the device for a very low threshold current density of 2.56 μA cm-2 due to the strong confinement of injected holes. The emission characteristics of the fabricated device with respect to the injected current density and temperature have been studied. Novel emission and optical modulation characteristics at 1550 nm of the fabricated p-i-n device containing Ge microdisks grown on a virtual SiGe substrate indicate its potential for Si CMOS compatible on-chip optical communications.
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Affiliation(s)
- Sudarshan Singh
- Department of Physics, Indian Institute of Technology, Kharagpur-721302 Kharagpur, India
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17
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Chen P, Murugappan K, Castell MR. Shapes of epitaxial gold nanocrystals on SrTiO3 substrates. Phys Chem Chem Phys 2020; 22:4416-4428. [DOI: 10.1039/c9cp06801e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Morphological control of gold nanocrystals is important as their catalytic and optical properties are highly shape dependent.
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Affiliation(s)
- Peiyu Chen
- Department of Materials
- University of Oxford
- Parks Road
- Oxford
- UK
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18
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Wang S, Zhang N, Chen P, Wang L, Yang X, Jiang Z, Zhong Z. Toward precise site-controlling of self-assembled Ge quantum dots on Si microdisks. NANOTECHNOLOGY 2018; 29:345606. [PMID: 29863488 DOI: 10.1088/1361-6528/aac9f6] [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
A feasible route is developed toward precise site-controlling of quantum dots (QDs) at the microdisk periphery, where most microdisk cavity modes are located. The preferential growth of self-assembled Ge QDs at the periphery of Si microdisks is discovered. Moreover, both the height and linear density of Ge QDs can be controlled by tuning the amount of deposited Ge and the microdisk size. The inherent mechanisms of these unique features are discussed, taking into account both the growth kinetics and thermodynamics. By growing Ge on the innovative Si microdisks with small protrusions at the disk periphery, the positioning of Ge QDs at the periphery can be exactly predetermined. Such a precise site-controlling of Ge QDs at the periphery enables the location of the QD right at the field antinodes of the cavity mode of the Si microdisk, thereby achieving spatial matching between QD and cavity mode. These results open a promising door to realize the semiconductor QD-microdisk systems with both spectral and spatial matching between QDs and microdisk cavity modes, which will be the promising candidates for exploring the fundamental features of cavity quantum electrodynamics and the innovative optoelectronic devices based on strong light-matter interaction.
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Affiliation(s)
- Shuguang Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
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19
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Liu X, Lin N, Cai W, Zhao Y, Zhou J, Liang J, Zhu Y, Qian Y. Mesoporous germanium nanoparticles synthesized in molten zinc chloride at low temperature as a high-performance anode for lithium-ion batteries. Dalton Trans 2018; 47:7402-7406. [DOI: 10.1039/c8dt01060a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mesoporous germanium nanoparticles are prepared by a “metathesis” reaction of magnesium germanide (Mg2Ge) and zinc chloride (ZnCl2), and they exhibit excellent electrochemical performance for Li-ion batteries.
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Affiliation(s)
- Xianyu Liu
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Ning Lin
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Wenlong Cai
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Yingyue Zhao
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Jianbin Zhou
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Jianwen Liang
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Yongchun Zhu
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Yitai Qian
- Hefei National Laboratory for Physical Science at Micro-scale
- Department of Chemistry
- University of Science and Technology of China
- Hefei
- P. R. China
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20
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Rutckaia V, Heyroth F, Novikov A, Shaleev M, Petrov M, Schilling J. Quantum Dot Emission Driven by Mie Resonances in Silicon Nanostructures. NANO LETTERS 2017; 17:6886-6892. [PMID: 28968505 DOI: 10.1021/acs.nanolett.7b03248] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Resonant dielectric nanostructures represent a promising platform for light manipulation at the nanoscale. In this paper, we describe an active photonic system based on Ge(Si) quantum dots coupled to silicon nanodisks. We show that Mie resonances govern the enhancement of the photoluminescent signal from embedded quantum dots due to a good spatial overlap of the emitter position with the electric field of Mie modes. We identify the coupling mechanism, which allows for engineering the resonant Mie modes through the interaction of several nanodisks. In particular, the mode hybridization in a nanodisk trimer results in an up to 10-fold enhancement of the luminescent signal due to the excitation of resonant antisymmetric magnetic and electric dipole modes.
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Affiliation(s)
- Viktoriia Rutckaia
- Centre for Innovation Competence SiLi-nano, Martin-Luther-University Halle-Wittenberg , Karl-Freiherr-von-Fritsch-Straße 3, 06120 Halle (Saale), Germany
- International Max Planck Research School for Science and Technology of Nanostructures , Weinberg 2, 06120 Halle (Saale), Germany
| | - Frank Heyroth
- Interdisciplinary Center of Material Science, Martin-Luther-University Halle-Wittenberg , Heinrich-Damerow-Straße 4, 06120 Halle (Saale), Germany
| | - Alexey Novikov
- Institute for Physics of Microstructures of the Russian Academy of Sciences (IPM RAS) , Academicheskaya Street 7, 603950 Nizhniy Novgorod, Russian Federation
| | - Mikhail Shaleev
- Institute for Physics of Microstructures of the Russian Academy of Sciences (IPM RAS) , Academicheskaya Street 7, 603950 Nizhniy Novgorod, Russian Federation
| | - Mihail Petrov
- Department of Nanophotonics and Metamaterials, ITMO University , Birzhevaya liniya 14, 199034 St. Petersburg, Russia
- Department of Physics and Mathematics, University of Eastern Finland , Yliopistokatu 7, 80101, Joensuu, Finland
| | - Joerg Schilling
- Centre for Innovation Competence SiLi-nano, Martin-Luther-University Halle-Wittenberg , Karl-Freiherr-von-Fritsch-Straße 3, 06120 Halle (Saale), Germany
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21
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Mezzasalma SA, Car T, Nekić N, Jerčinović M, Buljan M. Temperature behaviour of the average size of nanoparticle lattices co-deposited with an amorphous matrix. Analysis of Ge + Al 2O 3 and Ni + Al 2O 3 thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:435301. [PMID: 28699621 DOI: 10.1088/1361-648x/aa7f3c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We theoretically interpret the thermal behaviour of the average radius versus substrate temperature of regular quantum dot/nanocluster arrays formed by sputtering semiconductor/metal atoms with oxide molecules. The analysis relies on a continuum theory for amorphous films with given surface quantities, perturbed by a nanoparticle lattice. An account of the basic thermodynamic contributions is given in terms of force-flux phenomenological coefficients of each phase (Ge, Ni, Al2O3). Average radii turn out to be expressible by a characteristic length scale and a dimensionless parameter, which mainly depend upon temperature through diffusion lengths, film pressures and finite-size corrections to interfacial tensions. The numerical agreement is good in both Ge ([Formula: see text]) and Ni ([Formula: see text]) lattices grown at temperatures [Formula: see text]800 K, despite the lower temperature behaviour of quantum dots seeming to suggest further driving forces taking part in such processes.
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22
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Wei C, Spencer BJ. A Fokker-Planck reaction model for the epitaxial growth and shape transition of quantum dots. Proc Math Phys Eng Sci 2017; 473:20170308. [PMID: 29118661 PMCID: PMC5666231 DOI: 10.1098/rspa.2017.0308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 09/20/2017] [Indexed: 11/12/2022] Open
Abstract
We construct a Fokker-Planck reaction (FPR) model to investigate the dynamics of the coupled epitaxial growth and shape transition process of an array of quantum dots (QDs). The FPR model is based on a coupled system of Fokker-Planck equations wherein the distribution of each island type is governed by its own Fokker-Planck equation for growth, with reaction terms describing the shape transitions between islands of different types including asymmetric shapes. The reaction terms for the shape transitions depend on the island size and are determined from explicit calculations of the lowest barrier pathway for each shape transition. This mean-field model enables us to consider the kinetics of asymmetric shape transitions and study the evolution of island shape distributions during the coupled growth and transition process. Asymmetric metastable shapes play a crucial role in the dynamics, with asymmetric QDs comprising up to 10% of the population, and with up to 100% of the shape transitions passing through asymmetric shapes. Moreover, we find that the characteristic multimodal distribution of pyramid/dome QD coarsening can be eliminated at sufficiently high temperature and deposition rate.
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Affiliation(s)
| | - Brian J. Spencer
- Department of Mathematics, State University of New York at Buffalo, Buffalo, NY 14260-2900, USA
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23
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Brehm M, Grydlik M. Site-controlled and advanced epitaxial Ge/Si quantum dots: fabrication, properties, and applications. NANOTECHNOLOGY 2017; 28:392001. [PMID: 28729522 DOI: 10.1088/1361-6528/aa8143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this review, we report on fabrication paths, challenges, and emerging solutions to integrate group-IV epitaxial quantum dots (QDs) as active light emitters into the existing standard Si technology. Their potential as laser gain material for the use of optical intra- and inter-chip interconnects as well as possibilities to combine a single-photon-source-based quantum cryptographic means with Si technology will be discussed. We propose that the mandatory addressability of the light emitters can be achieved by a combination of organized QD growth assisted by templated self-assembly, and advanced inter-QD defect engineering to boost the optical emissivity of group-IV QDs at room-temperature. Those two main parts, the site-controlled growth and the light emission enhancement in QDs through the introduction of single defects build the main body of the review. This leads us to a roadmap for the necessary further development of this emerging field of CMOS-compatible group-IV QD light emitters for on-chip applications.
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24
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Salvalaglio M, Backofen R, Voigt A, Montalenti F. Morphological Evolution of Pit-Patterned Si(001) Substrates Driven by Surface-Energy Reduction. NANOSCALE RESEARCH LETTERS 2017; 12:554. [PMID: 28963645 PMCID: PMC5622022 DOI: 10.1186/s11671-017-2320-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 09/17/2017] [Indexed: 06/07/2023]
Abstract
Lateral ordering of heteroepitaxial islands can be conveniently achieved by suitable pit-patterning of the substrate prior to deposition. Controlling shape, orientation, and size of the pits is not trivial as, being metastable, they can significantly evolve during deposition/annealing. In this paper, we exploit a continuum model to explore the typical metastable pit morphologies that can be expected on Si(001), depending on the initial depth/shape. Evolution is predicted using a surface-diffusion model, formulated in a phase-field framework, and tackling surface-energy anisotropy. Results are shown to nicely reproduce typical metastable shapes reported in the literature. Moreover, long time scale evolutions of pit profiles with different depths are found to follow a similar kinetic pathway. The model is also exploited to treat the case of heteroepitaxial growth involving two materials characterized by different facets in their equilibrium Wulff's shape. This can lead to significant changes in morphologies, such as a rotation of the pit during deposition as evidenced in Ge/Si experiments.
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Affiliation(s)
- Marco Salvalaglio
- Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany.
- IHP, Im Technologiepark 25, Frankfurt (Oder), 15236, Germany.
| | - Rainer Backofen
- Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany
| | - Axel Voigt
- Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany
- Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany
| | - Francesco Montalenti
- L-NESS and Department of Materials Science, Università di Milano-Bicocca, via R. Cozzi 55, Milano, I-20126, Italy
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25
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Wang Z, Wang S, Yin Y, Liu T, Lin D, Li DH, Yang X, Jiang Z, Zhong Z. Promising features of low-temperature grown Ge nanostructures on Si(001) substrates. NANOTECHNOLOGY 2017; 28:115701. [PMID: 28140355 DOI: 10.1088/1361-6528/aa5b3d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
High-quality Ge nanostructures are obtained by molecular beam epitaxy of Ge on Si(001) substrates at 200 °C and ex situ annealing at 400 °C. Their structural properties are comprehensively characterized by atomic force microscopy, transmission electron microscopy and Raman spectroscopy. It is disclosed that they are almost defect free except for some defects at the Ge/Si interface and in the subsequent Si capping layer. The misfit strain in the nanostructure is substantially relaxed. Dramatically strong photoluminescence (PL) from the Ge nanostructures is observed. Detailed analyses on the power- and temperature-dependent PL spectra, together with a self-consistent calculation, indicate the confinement and the high quantum efficiency of excitons within the Ge nanostructures. Our results demonstrate that the Ge nanostructures obtained via the present feasible route may have great potential in optoelectronic devices for monolithic optical-electronic integration circuits.
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Affiliation(s)
- Ze Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
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26
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Shklyaev AA, Latyshev AV. Surface Morphology Transformation Under High-Temperature Annealing of Ge Layers Deposited on Si(100). NANOSCALE RESEARCH LETTERS 2016; 11:366. [PMID: 27541814 PMCID: PMC4991982 DOI: 10.1186/s11671-016-1588-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/16/2016] [Indexed: 06/06/2023]
Abstract
We study the surface morphology and chemical composition of SiGe layers after their formation under high-temperature annealing at 800-1100 °C of 30-150 nm Ge layers deposited on Si(100) at 400-500 °C. It is found that the annealing leads to the appearance of the SiGe layers of two types, i.e., porous and continuous. The continuous layers have a smoothened surface morphology and a high concentration of threading dislocations. The porous and continuous layers can coexist. Their formation conditions and the ratio between their areas on the surface depend on the thickness of deposited Ge layers, as well as on the temperature and the annealing time. The data obtained suggest that the porous SiGe layers are formed due to melting of the strained Ge layers and their solidification in the conditions of SiGe dewetting on Si. The porous and dislocation-rich SiGe layers may have properties interesting for applications.
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Affiliation(s)
- A A Shklyaev
- A.V. Rzhanov Institute of Semiconductor Physics, SB RAS, Novosibirsk, 630090, Russia.
- Novosibirsk State University, Novosibirsk, 630090, Russia.
| | - A V Latyshev
- A.V. Rzhanov Institute of Semiconductor Physics, SB RAS, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
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27
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Ponomaryov SS, Yukhymchuk VO, Lytvyn PM, Valakh MY. Direct Determination of 3D Distribution of Elemental Composition in Single Semiconductor Nanoislands by Scanning Auger Microscopy. NANOSCALE RESEARCH LETTERS 2016; 11:103. [PMID: 26909783 PMCID: PMC4766170 DOI: 10.1186/s11671-016-1308-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/11/2016] [Indexed: 06/05/2023]
Abstract
An application of scanning Auger microscopy with ion etching technique and effective compensation of thermal drift of the surface analyzed area is proposed for direct local study of composition distribution in the bulk of single nanoislands. For GexSi1 - x-nanoislands obtained by MBE of Ge on Si-substrate gigantic interdiffusion mixing takes place both in the open and capped nanostructures. Lateral distributions of the elemental composition as well as concentration-depth profiles were recorded. 3D distribution of the elemental composition in the d-cluster bulk was obtained using the interpolation approach by lateral composition distributions in its several cross sections and concentration-depth profile. It was shown that there is a germanium core in the nanoislands of both nanostructure types, which even penetrates the substrate. In studied nanostructures maximal Ge content in the nanoislands may reach about 40 at.%.
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Affiliation(s)
- Semyon S Ponomaryov
- Institute of Semiconductor Physics, NASU, Pr. Nauky 41, Kyiv, 03028, Ukraine.
| | | | - Peter M Lytvyn
- Institute of Semiconductor Physics, NASU, Pr. Nauky 41, Kyiv, 03028, Ukraine.
| | - Mykhailo Ya Valakh
- Institute of Semiconductor Physics, NASU, Pr. Nauky 41, Kyiv, 03028, Ukraine.
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28
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Zhang Y, Chen Z, Xu GQ. Morphological evolution of Ge islands on the Si(100) surface: from huts to pits. SURF INTERFACE ANAL 2016. [DOI: 10.1002/sia.6143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yongping Zhang
- Faculty of Materials and Energy; Southwest University; Chongqing 400715 China
| | - Zhiqian Chen
- Faculty of Materials and Energy; Southwest University; Chongqing 400715 China
| | - Guo Qin Xu
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543
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29
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Ren XY, Kim HJ, Niu CY, Jia Y, Cho JH. Origin of Symmetric Dimer Images of Si(001) Observed by Low-Temperature Scanning Tunneling Microscopy. Sci Rep 2016; 6:27868. [PMID: 27292000 PMCID: PMC4904415 DOI: 10.1038/srep27868] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 05/26/2016] [Indexed: 11/09/2022] Open
Abstract
It has been a long-standing puzzle why buckled dimers of the Si(001) surface appeared symmetric below ~20 K in scanning tunneling microscopy (STM) experiments. Although such symmetric dimer images were concluded to be due to an artifact induced by STM measurements, its underlying mechanism is still veiled. Here, we demonstrate, based on a first-principles density-functional theory calculation, that the symmetric dimer images are originated from the flip-flop motion of buckled dimers, driven by quantum tunneling (QT). It is revealed that at low temperature the tunneling-induced surface charging with holes reduces the energy barrier for the flipping of buckled dimers, thereby giving rise to a sizable QT-driven frequency of the flip-flop motion. However, such a QT phenomenon becomes marginal in the tunneling-induced surface charging with electrons. Our findings provide an explanation for low-temperature STM data that exhibits apparent symmetric (buckled) dimer structure in the filled-state (empty-state) images.
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Affiliation(s)
- Xiao-Yan Ren
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.,Department of Physics and Research Institute for Natural Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.,School of Mechanical and Electrical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Hyun-Jung Kim
- Department of Physics and Research Institute for Natural Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.,Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722, Korea
| | - Chun-Yao Niu
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.,Center for Advanced Analysis and Computational Science, Zhengzhou University, Zhengzhou 45001, China
| | - Yu Jia
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.,Center for Advanced Analysis and Computational Science, Zhengzhou University, Zhengzhou 45001, China
| | - Jun-Hyung Cho
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.,Department of Physics and Research Institute for Natural Sciences, Hanyang University, 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea.,International Center for Quantum Design of Functional Materials (ICQD), HFNL, University of Science and Technology of China, Hefei, Anhui 230026, China
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30
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Hu H, Niu X, Liu F. Thermodynamic Self-Limiting Growth of Heteroepitaxial Islands Induced by Nonlinear Elastic Effect. NANO LETTERS 2016; 16:3919-3924. [PMID: 27203611 DOI: 10.1021/acs.nanolett.6b01525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate nonlinear elastic effect (NLEF) on the growth of heteroepitaxial islands, a topic of both scientific and technological significance for their applications as quantum dots. We show that the NLEF induces a thermodynamic self-limiting growth mechanism that hinders the strain relaxation of coherent island beyond a maximum size, which is in contrast to indefinite strain relaxation with increasing island size in the linear elastic regime. This self-limiting growth effect shows a strong dependence on the island facet angle, which applies also to islands inside pits patterned in a substrate surface with an additional dependence on the pit inclination angle. Consequently, primary islands nucleate and grow first in the pits and then secondary islands nucleate at the rim around the pits after the primary islands reach the self-limited maximum size. Our theory sheds new lights on understanding the heteroepitaxial island growth and explains a number of past and recent experimental observations.
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Affiliation(s)
- Hao Hu
- Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an 710054, China
| | - Xiaobin Niu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah , Salt Lake City, Utah 84112, United States
- Collaborative Innovation Center of Quantum Matter , Beijing 100084, China
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31
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Zhou T, Zhong Z. Towards promising modification of GeSi nanostructures via self-assembly on miscut Si(001) substrates. NANOTECHNOLOGY 2016; 27:115601. [PMID: 26871257 DOI: 10.1088/0957-4484/27/11/115601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Self-assembled GeSi nanostructures on miscut Si(001) substrates are studied systematically with regard to the miscut angle and azimuth, the amount of Ge and the growth temperature. The comprehensive dependence of the spatial arrangement, which can exhibit one- and two-dimensional (1D and 2D) ordering, as well as the shape and density, of GeSi nanostructures on the miscut angle is observed. The orientation and side-walls of the 1D ordered in-plane GeSi nanowires on miscut Si(001) substrates are intimately associated with the miscut azimuth towards the 〈110〉 or 〈010〉 directions. Furthermore, the unique evolution of the GeSi nanostructures with the amount of Ge and the growth temperature on miscut Si (001) substrates towards the 〈010〉 direction is discovered. Such promising features of self-assembled GeSi nanostructures on miscut Si (001) substrates are explained in terms of the thermodynamics and growth kinetics, which are both affected significantly by the substrate vicinality. These results demonstrate that the miscut substrates offer a promising degree of freedom for the feasible modification of self-assembled nanostructures.
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Affiliation(s)
- Tong Zhou
- State Key Laboratory of Surface Physics and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, People's Republic of China. School of Science, Shandong University of Technology, Zibo 255049, People's Republic of China
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32
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Grydlik M, Hackl F, Groiss H, Glaser M, Halilovic A, Fromherz T, Jantsch W, Schäffler F, Brehm M. Lasing from Glassy Ge Quantum Dots in Crystalline Si. ACS PHOTONICS 2016; 3:298-303. [PMID: 26937421 PMCID: PMC4759615 DOI: 10.1021/acsphotonics.5b00671] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 05/25/2023]
Abstract
Semiconductor light-emitters compatible with standard Si integration technology (SIT) are of particular interest for overcoming limitations in the operating speed of microelectronic devices. Light sources based on group IV elements would be SIT-compatible, but suffer from the poor optoelectronic properties of bulk Si and Ge. Here we demonstrate that epitaxially grown Ge quantum dots (QDs) in a defect-free Si matrix show extraordinary optical properties if partially amorphized by Ge-ion bombardment (GIB). In contrast to conventional SiGe nanostructures, these QDs exhibit dramatically shortened carrier lifetimes and negligible thermal quenching of the photoluminescence (PL) up to room temperature. Microdisk resonators with embedded GIB-QDs exhibit threshold behavior as well as a superlinear increase of the integrated PL intensity with concomitant line width narrowing as the pump power increases. These findings demonstrate light amplification by stimulated emission in a fully SIT-compatible group IV nanosystem.
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Affiliation(s)
| | - Florian Hackl
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Heiko Groiss
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Martin Glaser
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Alma Halilovic
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Thomas Fromherz
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Wolfgang Jantsch
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Friedrich Schäffler
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
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33
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Marks LD, Peng L. Nanoparticle shape, thermodynamics and kinetics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:053001. [PMID: 26792459 DOI: 10.1088/0953-8984/28/5/053001] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Nanoparticles can be beautiful, as in stained glass windows, or they can be ugly as in wear and corrosion debris from implants. We estimate that there will be about 70,000 papers in 2015 with nanoparticles as a keyword, but only one in thirteen uses the nanoparticle shape as an additional keyword and research focus, and only one in two hundred has thermodynamics. Methods for synthesizing nanoparticles have exploded over the last decade, but our understanding of how and why they take their forms has not progressed as fast. This topical review attempts to take a critical snapshot of the current understanding, focusing more on methods to predict than a purely synthetic or descriptive approach. We look at models and themes which are largely independent of the exact synthetic method whether it is deposition, gas-phase condensation, solution based or hydrothermal synthesis. Elements are old dating back to the beginning of the 20th century-some of the pioneering models developed then are still relevant today. Others are newer, a merging of older concepts such as kinetic-Wulff constructions with methods to understand minimum energy shapes for particles with twins. Overall we find that while there are still many unknowns, the broad framework of understanding and predicting the structure of nanoparticles via diverse Wulff constructions, either thermodynamic, local minima or kinetic has been exceedingly successful. However, the field is still developing and there remain many unknowns and new avenues for research, a few of these being suggested towards the end of the review.
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Affiliation(s)
- L D Marks
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
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Niu G, Capellini G, Lupina G, Niermann T, Salvalaglio M, Marzegalli A, Schubert MA, Zaumseil P, Krause HM, Skibitzki O, Lehmann M, Montalenti F, Xie YH, Schroeder T. Photodetection in Hybrid Single-Layer Graphene/Fully Coherent Germanium Island Nanostructures Selectively Grown on Silicon Nanotip Patterns. ACS APPLIED MATERIALS & INTERFACES 2016; 8:2017-2026. [PMID: 26709534 DOI: 10.1021/acsami.5b10336] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Dislocation networks are one of the most principle sources deteriorating the performances of devices based on lattice-mismatched heteroepitaxial systems. We demonstrate here a technique enabling fully coherent germanium (Ge) islands selectively grown on nanotip-patterned Si(001) substrates. The silicon (Si)-tip-patterned substrate, fabricated by complementary metal oxide semiconductor compatible nanotechnology, features ∼50-nm-wide Si areas emerging from a SiO2 matrix and arranged in an ordered lattice. Molecular beam epitaxy growths result in Ge nanoislands with high selectivity and having homogeneous shape and size. The ∼850 °C growth temperature required for ensuring selective growth has been shown to lead to the formation of Ge islands of high crystalline quality without extensive Si intermixing (with 91 atom % Ge). Nanotip-patterned wafers result in geometric, kinetic-diffusion-barrier intermixing hindrance, confining the major intermixing to the pedestal region of Ge islands, where kinetic diffusion barriers are, however, high. Theoretical calculations suggest that the thin Si/Ge layer at the interface plays, nevertheless, a significant role in realizing our fully coherent Ge nanoislands free from extended defects especially dislocations. Single-layer graphene/Ge/Si-tip Schottky junctions were fabricated, and thanks to the absence of extended defects in Ge islands, they demonstrate high-performance photodetection characteristics with responsivity of ∼45 mA W(-1) and an Ion/Ioff ratio of ∼10(3).
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Affiliation(s)
- Gang Niu
- IHP , Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University , Xi'an 710049, China
| | - Giovanni Capellini
- IHP , Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
- Dipartimento di Scienze, Università Roma Tre , Viale Marconi 446, 00146 Rome, Italy
| | - Grzegorz Lupina
- IHP , Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
| | - Tore Niermann
- Technische Universität Berlin, Institut für Optik und Atomare Physik , Straße des 17 Juni 135, 10623 Berlin, Germany
| | - Marco Salvalaglio
- L-NESS and Department of Materials Science, Università degli Studi di Milano-Bicocca , via Cozzi 55, I-20125 Milan, Italy
| | - Anna Marzegalli
- L-NESS and Department of Materials Science, Università degli Studi di Milano-Bicocca , via Cozzi 55, I-20125 Milan, Italy
| | | | - Peter Zaumseil
- IHP , Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
| | | | | | - Michael Lehmann
- Technische Universität Berlin, Institut für Optik und Atomare Physik , Straße des 17 Juni 135, 10623 Berlin, Germany
| | - Francesco Montalenti
- L-NESS and Department of Materials Science, Università degli Studi di Milano-Bicocca , via Cozzi 55, I-20125 Milan, Italy
| | - Ya-Hong Xie
- Department of Materials Science and Engineering, University of California at Los Angeles , Los Angeles, California 90095-1595, United States
| | - Thomas Schroeder
- IHP , Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
- BTU Cottbus-Senftenberg , Konrad-Zuse-Straße 1, 03046 Cottbus, Germany
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35
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Wang L, Bao K, Lou Z, Liang G, Zhou Q. Chemical synthesis of germanium nanoparticles with uniform size as anode materials for lithium ion batteries. Dalton Trans 2016; 45:2814-7. [DOI: 10.1039/c5dt04749h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple Mg-thermal reduction reaction is reported to synthesize germanium (Ge) nanoparticles with a uniform size at a low temperature of 400 °C in an autoclave.
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Affiliation(s)
- Liangbiao Wang
- Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering
- School of Chemistry and Environment Engineering
- Jiangsu University of Technology
- Changzhou 213001
- China
| | - Keyan Bao
- College of Chemistry and Pharmacy Engineering
- Nanyang Normal University
- Nanyang 473061
- China
| | - Zhengsong Lou
- Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering
- School of Chemistry and Environment Engineering
- Jiangsu University of Technology
- Changzhou 213001
- China
| | - Guobing Liang
- Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering
- School of Chemistry and Environment Engineering
- Jiangsu University of Technology
- Changzhou 213001
- China
| | - Quanfa Zhou
- Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering
- School of Chemistry and Environment Engineering
- Jiangsu University of Technology
- Changzhou 213001
- China
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36
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Brehm M, Groiss H, Bauer G, Gerthsen D, Clarke R, Paltiel Y, Yacoby Y. Atomic structure and composition distribution in wetting layers and islands of germanium grown on silicon (001) substrates. NANOTECHNOLOGY 2015; 26:485702. [PMID: 26553384 DOI: 10.1088/0957-4484/26/48/485702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We present a comprehensive structural investigation of the Ge wetting layer (WL) and island growth on Si(001) substrates by a combination of AFM, high resolution transmission electron microscopy and the energy-differential coherent Bragg rod analysis (COBRA) x-ray method. By considering the influence of the initial Si surface morphology on the deposited Ge, these techniques provide quantitative information on the Ge content and its distribution, in particular within the WL which plays a crucial role in the formation of epitaxial nanostructures. In the WL, the Ge content was found to be above 80% for our growth conditions. Furthermore, from the digital analysis of high-resolution transmission electron microscope images, quantitative information on the strain relaxation is obtained, which complements the COBRA analysis of the Ge distribution and content in these nanostructures.
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Affiliation(s)
- Moritz Brehm
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, 4040 Linz, Austria
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37
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Chen H, Wang J, Ashalley E, Li H, Niu X. Calculation of Elastic Bond Constants in Atomistic Strain Analysis. NANOSCALE RESEARCH LETTERS 2015; 10:403. [PMID: 26474884 PMCID: PMC4608958 DOI: 10.1186/s11671-015-1109-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/07/2015] [Indexed: 06/05/2023]
Abstract
Strain analysis has significance both for tailoring material properties and designing nanoscale devices. In particular, strain plays a vital role in engineering the growth thermodynamics and kinetics and is applicable for designing optoelectronic devices. In this paper, we present a methodology for establishing the relationship between elastic bond constants and measurable parameters, i.e., Poisson's ratio ν and systematic elastic constant K. At the atomistic level, this approach is within the framework of linear elastic theory and encompasses the neighbor interactions when an atom is introduced to stress. Departing from the force equilibrium equations, the relationships between ν, K, and spring constants are successfully established. Both the two-dimensional (2D) square lattice and common three-dimensional (3D) structures are taken into account in the procedure for facilitating, bridging the gap between structural complexity and numerical experiments. A new direction for understanding the physical phenomena in strain engineering is established.
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Affiliation(s)
- Haiyuan Chen
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Juanjuan Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Eric Ashalley
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Handong Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xiaobin Niu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China.
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38
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Zhang Z, Wang Z, He S, Wang C, Jin M, Yin Y. Redox reaction induced Ostwald ripening for size- and shape-focusing of palladium nanocrystals. Chem Sci 2015; 6:5197-5203. [PMID: 29449925 PMCID: PMC5669216 DOI: 10.1039/c5sc01787d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 06/18/2015] [Indexed: 11/21/2022] Open
Abstract
We report here that size- and shape-focusing can be achieved through the well-known Ostwald ripening process to produce high-quality metal nanocrystals (NCs). Using Pd as an example, we show that the addition of small NCs of appropriate sizes could help in modulating the growth of larger NCs and enable excellent control over both the size and shape uniformity of the products. A detailed mechanistic study showed that the self-focusing of Pd NCs relied on a dissolution and regrowth process induced by redox reaction of HCHO. With the assistance of HCHO, injection of small sacrificial nanocrystals (SNCs), with sizes below a critical value, into larger seeds results in the dissolution of the SNCs and subsequent deposition onto the larger ones, thus allowing the formation of monodisperse Pd NCs. We have identified the critical radius of the SNCs to be ∼5.7 nm for Pd, and verified that SNCs with sizes larger than that could not effectively support the growth of larger seeds. More interestingly, since Ostwald ripening involves matter relocation, this synthetic approach could even break the self-termination growth habits of metal NCs and produce nanocrystals with sizes that are not conveniently accessible by direct growth.
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Affiliation(s)
- Zhaorui Zhang
- Frontier Institute of Science and Technology , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710054 , P. R. China .
| | - Zhenni Wang
- Frontier Institute of Science and Technology , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710054 , P. R. China .
| | - Shengnan He
- Frontier Institute of Science and Technology , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710054 , P. R. China .
| | - Chaoqi Wang
- Frontier Institute of Science and Technology , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710054 , P. R. China .
| | - Mingshang Jin
- Frontier Institute of Science and Technology , State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710054 , P. R. China .
| | - Yadong Yin
- Department of Chemistry , University of California , Riverside , California 92521 , USA .
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39
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Persichetti L, Sgarlata A, Fanfoni M, Balzarotti A. Heteroepitaxy of Ge on singular and vicinal Si surfaces: elastic field symmetry and nanostructure growth. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:253001. [PMID: 26021279 DOI: 10.1088/0953-8984/27/25/253001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Starting with the basic definition, a short description of a few relevant physical quantities playing a role in the growth process of heteroepitaxial strained systems, is provided. As such, the paper is not meant to be a comprehensive survey but to present a connection between the Stranski-Krastanov mechanism of nanostructure formation and the basic principles of nucleation and growth. The elastic field is described in the context of continuum elasticity theory, using either analytical models or numerical simulations. The results are compared with selected experimental results obtained on GeSi nanostructures. In particular, by tuning the value of quantities such as vicinality, substrate orientation and symmetry of the diffusion field, we elucidate how anisotropic elastic interactions determine shape, size, lateral distribution and composition of quantum dots.
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Affiliation(s)
- L Persichetti
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH - 8093 Zürich, Switzerland
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40
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Frigge T, Hafke B, Tinnemann V, Witte T, Horn-von Hoegen M. Spot profile analysis and lifetime mapping in ultrafast electron diffraction: Lattice excitation of self-organized Ge nanostructures on Si(001). STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2015; 2:035101. [PMID: 26798797 PMCID: PMC4711617 DOI: 10.1063/1.4922023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 05/22/2015] [Indexed: 06/05/2023]
Abstract
Ultrafast high energy electron diffraction in reflection geometry is employed to study the structural dynamics of self-organized Germanium hut-, dome-, and relaxed clusters on Si(001) upon femtosecond laser excitation. Utilizing the difference in size and strain state the response of hut- and dome clusters can be distinguished by a transient spot profile analysis. Surface diffraction from {105}-type facets provide exclusive information on hut clusters. A pixel-by-pixel analysis of the dynamics of the entire diffraction pattern gives time constants of 40, 160, and 390 ps, which are assigned to the cooling time constants for hut-, dome-, and relaxed clusters.
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Affiliation(s)
- T Frigge
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - B Hafke
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - V Tinnemann
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - T Witte
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
| | - M Horn-von Hoegen
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen , Lotharstr. 1, 47057 Duisburg, Germany
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41
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Pandey P, Sui M, Li MY, Zhang Q, Kim ES, Lee J. Shape transformation of self-assembled Au nanoparticles by the systematic control of deposition amount on sapphire (0001). RSC Adv 2015. [DOI: 10.1039/c5ra07631e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The shape and size dependent optical, physical and chemical properties of isotropic and anisotropic gold nanoparticles (Au NPs) have attracted significant research interest for their application in various optoelectronic devices.
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Affiliation(s)
- Puran Pandey
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
| | - Mao Sui
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
| | - Ming-Yu Li
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
| | - Quanzhen Zhang
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
| | - Eun-Soo Kim
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
| | - Jihoon Lee
- College of Electronics and Information
- Kwangwoon University
- Seoul 139-701
- South Korea
- Institute of Nanoscale Science and Engineering
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42
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Chen HM, Suen YW, Chen SJ, Luo GL, Lai YP, Chen ST, Lee CH, Kuan CH. Effect of surface Si redistribution on the alignment of Ge dots grown on pit-patterned Si(001) substrates. NANOTECHNOLOGY 2014; 25:475301. [PMID: 25369731 DOI: 10.1088/0957-4484/25/47/475301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Thermally activated redistribution of Si surface atoms is found to be a crucial factor for the growth of aligned Ge dots on pit-patterned Si(001) substrates. A phenomenon of Si accumulation around the edge of pits significantly alters the substrate surface morphology. As the pit spacing is reduced to below 100 nm, a convex morphology developed between adjacent pits causes a chemical potential distribution that drives the Ge dots into the pits. In addition, the pits of an etching depth greater than 60 nm will evolve into truncated inverted pyramids with sharp base corners that provide deep potential wells for the confinement of Ge dots. Perfectly aligned Ge dots are obtained on pit-patterned Si substrates with this range of pit spacing and etching depth. We also find that the initial geometric shape of the pits does not affect the spatial arrangement of Ge dots.
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Affiliation(s)
- Hung-Ming Chen
- Graduate Institute of Electronics Engineering and Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan, Republic of China
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Zhang J, Brehm M, Grydlik M, Schmidt OG. Evolution of epitaxial semiconductor nanodots and nanowires from supersaturated wetting layers. Chem Soc Rev 2014; 44:26-39. [PMID: 24853640 DOI: 10.1039/c4cs00077c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this tutorial we review recent progress in the design and growth of epitaxial semiconductor nanostructures in lattice-mismatched material systems. We focus on the Ge on Si model system after pointing out the similarities to III-V and other growth systems qualitatively as well as quantitatively. During material deposition, the first layers of the epitaxial film wet the surface before the formation of strain-driven three-dimensional nanostructures. In particular, we stress that the supersaturation of the wetting layer (WL), whose relevance is often neglected, plays a key role in determining the nucleation and growth of nanodots (NDs), nanodot-molecules and nanowires (NWs). At elevated growth temperatures the Ge reservoir in the planar, supersaturated WL is abruptly consumed and generates NDs with highly homogeneous sizes - a process mainly driven by elastic energy minimization. Furthermore, the careful control of the supersaturated Ge layer allows us to obtain perfectly site-controlled, ordered NDs or ND-molecules on pit-patterned substrates for a broad range of pit-periods. At low growth temperatures subtle interplays between surface energies of dominant crystal facets in the system drive the material transfer from the supersaturated WL into the elongating NWs growing horizontally, dislocation- and catalyst-free on the substrate surface. Due to the similarities in the formation of nanostructures in different epitaxial semiconductor systems we expect that the observation of the novel growth phenomena described in this Tutorial Review for Ge/Si should be relevant for other lattice-mismatched heterostructure systems, too.
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Affiliation(s)
- Jianjun Zhang
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
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Vanacore GM, Zani M, Bollani M, Bonera E, Nicotra G, Osmond J, Capellini G, Isella G, Tagliaferri A. Monitoring the kinetic evolution of self-assembled SiGe islands grown by Ge surface thermal diffusion from a local source. NANOTECHNOLOGY 2014; 25:135606. [PMID: 24594569 DOI: 10.1088/0957-4484/25/13/135606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this paper we experimentally study the growth of self-assembled SiGe islands formed on Si(001) by exploiting the thermally activated surface diffusion of Ge atoms from a local Ge source stripe in the temperature range 600-700 °C. This new growth strategy allows us to vary continuously the Ge coverage from 8 to 0 monolayers as the distance from the source increases, and thus enables the investigation of the island growth over a wide range of dynamical regimes at the same time, providing a unique birds eye view of the factors governing the growth process and the dominant mechanism for the mass collection by a critical nucleus. Our results give experimental evidence that the nucleation process evolves within a diffusion limited regime. At a given annealing temperature, we find that the nucleation density depends only on the kinetics of the Ge surface diffusion resulting in a universal scaling distribution depending only on the Ge coverage. An analytical model is able to reproduce quantitatively the trend of the island density. Following the nucleation, the growth process appears to be driven mainly by short-range interactions between an island and the atoms diffusing within its vicinities. The islands volume distribution is, in fact, well described in the whole range of parameters by the Mulheran's capture zone model. The complex growth mechanism leads to a strong intermixing of Si and Ge within the island volume. Our growth strategy allows us to directly investigate the correlation between the Si incorporation and the Ge coverage in the same experimental conditions: higher intermixing is found for lower Ge coverage. This confirms that, besides the Ge gathering from the surface, also the Si incorporation from the substrate is driven by the diffusion kinetics, thus imposing a strict constraint on the initial Ge coverage, its diffusion properties and the final island volume.
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Affiliation(s)
- G M Vanacore
- CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
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45
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Marshall MSJ, Castell MR. Scanning tunnelling microscopy of epitaxial nanostructures. Chem Soc Rev 2014; 43:2226-39. [DOI: 10.1039/c3cs60458f] [Citation(s) in RCA: 13] [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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46
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Russo-Averchi E, Dalmau-Mallorquí A, Canales-Mundet I, Tütüncüoğlu G, Alarcon-Llado E, Heiss M, Rüffer D, Conesa-Boj S, Caroff P, Fontcuberta i Morral A. Growth mechanisms and process window for InAs V-shaped nanoscale membranes on Si[001]. NANOTECHNOLOGY 2013; 24:435603. [PMID: 24107441 DOI: 10.1088/0957-4484/24/43/435603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Organized growth of high aspect-ratio nanostructures such as membranes is interesting for opto-electronic and energy harvesting applications. Recently, we reported a new form of InAs nano-membranes grown on Si substrates with enhanced light scattering properties. In this paper we study how to tune the morphology of the membranes by changing the growth conditions. We examine the role of the V/III ratio, substrate temperature, mask opening size and inter-hole distances in determining the size and shape of the structures. Our results show that the nano-membranes form by a combination of the growth mechanisms of nanowires and the Stranski-Krastanov type of quantum dots: in analogy with nanowires, the length of the membranes strongly depends on the growth temperature and the V/III ratio; the inter-hole distance of the sample determines two different growth regimes: competitive growth for small distances and an independent regime for larger distances. Conversely, and similarly to quantum dots, the width of the nano-membranes increases with the growth temperature and does not exhibit dependence on the V/III ratio. These results constitute an important step towards achieving rational design of high aspect-ratio nanostructures.
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Affiliation(s)
- E Russo-Averchi
- Laboratoire des Matériaux Semiconducteurs, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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47
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Hrauda N, Zhang JJ, Groiss H, Etzelstorfer T, Holý V, Bauer G, Deiter C, Seeck OH, Stangl J. Strain relief and shape oscillations in site-controlled coherent SiGe islands. NANOTECHNOLOGY 2013; 24:335707. [PMID: 23892543 DOI: 10.1088/0957-4484/24/33/335707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Strain engineering and the crystalline quality of semiconductor nanostructures are important issues for electronic and optoelectronic devices. We report on defect-free SiGe island arrays resulting from Ge coverages of up to 38 monolayers grown on prepatterned Si(001) substrates. This represents a significant expansion of the parameter space known for the growth of perfect island arrays. A cyclic development of the Ge content and island shape was observed while increasing the Ge coverage. Synchrotron-based x-ray diffraction experiments and finite element method calculations allow us to study the strain behavior of such islands in great detail. In contrast to the oscillatory changes of island shape and average Ge content, the overall strain behavior of these islands exhibits a clear monotonic trend of progressive strain relaxation with increasing Ge coverage.
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Affiliation(s)
- N Hrauda
- Institute for Semiconductor Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria.
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48
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Shchukin V, Ledentsov N, Rouvimov S. Formation of three-dimensional islands in subcritical layer deposition in Stranski-Krastanow growth. PHYSICAL REVIEW LETTERS 2013; 110:176101. [PMID: 23679747 DOI: 10.1103/physrevlett.110.176101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 03/08/2013] [Indexed: 06/02/2023]
Abstract
A new method for the formation of three-dimensional (3D) strained islands in lattice-mismatched (B on A) heteroepitaxy is proposed. Once B forms a wetting layer of a subcritical thickness, material C is deposited, which is lattice matched to A and does not wet B. Then B and C phase separate forming local B-rich and C-rich domains on the surface. The thickness of B-rich domains thus exceeds locally that of the initial film of B, and 3D islands may form as it is demonstrated by modeled phase diagrams of the C/B/A system. We show that the growth of the subcritical InAs/GaAs(100) film followed by the deposition of AlAs results (i) in the formation of Al-rich and In-rich domains in the wetting layer, confirmed by chemically sensitive scanning transmission electron microscopy, and (ii) in the stimulated onset of 3D islands, as evidenced both by high resolution transmission electron microscopy and by a significant redshift of the photoluminescence spectrum, which is in agreement with the proposed model.
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Affiliation(s)
- V Shchukin
- VI Systems GmbH, Hardenbergstraße 7, Berlin D-10623, Germany.
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49
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Scopece D. SOWOS: an open-source program for the three-dimensional Wulff construction. J Appl Crystallogr 2013. [DOI: 10.1107/s0021889813005426] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A Fortran90 program for the determination of the Wulff construction, starting solely from the directions of the bounding facets (defined by the user), is presented.SOWOSstands for solid of Wulff open source, and the program is distributed freely with no charge to the user, being readily available to the community for immediate use. Its simple algorithm (which will be explained) allows the determination of complex solids with hundreds of facets in just seconds on any machine, requiring only a small amount of memory. It is able to determine even the smallest facets and shortest edges and to distinguish almost adjacent vertices. The output files give a complete range of information about the structure: the coordinates of the vertices and the facets common to them, the extension of the facets and bounding vertices, and the length of the edges and extreme vertices. These details enable the reconstruction of the shape in any other (commercial) software for further processing. Visualization is straightforwardviathe free programgnuplot. A feature for the creation of cubic crystal atomistic models of the resultant solids is included. The program may be a useful tool for crystallography, nanostructures and any other field where crystal facets are involved.
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Grydlik M, Langer G, Fromherz T, Schäffler F, Brehm M. Recipes for the fabrication of strictly ordered Ge islands on pit-patterned Si(001) substrates. NANOTECHNOLOGY 2013; 24:105601. [PMID: 23416837 DOI: 10.1088/0957-4484/24/10/105601] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We identify the most important parameters for the growth of ordered SiGe islands on pit-patterned Si(001) substrates. From a multi-dimensional parameter space we link individual contributions to isolate their influence on ordered island growth. This includes the influences of: the pit size, pit depth and pit period on the Si buffer layer and subsequent Ge growth; the pit sidewall inclination on Ge island growth; the amount of Ge on island morphologies as well as the influences of the pit-size homogeneity, the pit period, the Ge growth temperature and rate on island formation. We highlight that the initial pit shape and pit size in combination with the growth conditions of the Si buffer layer should be adjusted to provide suitable preconditions for the growth of Ge islands with the desired size, composition and nucleation position. Furthermore, we demonstrate that the wetting layer between pits can play the role of a stabilizer that inhibits shape transformations of ordered islands. Thus, dislocation formation within islands can be delayed, uniform arrays of one island type can be fabricated and secondary island nucleation between pits can be impeded. These findings allow us to fabricate perfectly ordered and homogeneous Ge islands on one and the same sample, even if the pit period is varied from a few hundred nanometres to several micrometres.
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Affiliation(s)
- Martyna Grydlik
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Austria
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