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Garcia-Gil A, Biswas S, Holmes JD. A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2002. [PMID: 34443831 PMCID: PMC8398625 DOI: 10.3390/nano11082002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/23/2021] [Accepted: 07/30/2021] [Indexed: 12/14/2022]
Abstract
Ge nanowires are playing a big role in the development of new functional microelectronic modules, such as gate-all-around field-effect transistor devices, on-chip lasers and photodetectors. The widely used three-phase bottom-up growth method utilising a foreign catalyst metal or metalloid is by far the most popular for Ge nanowire growth. However, to fully utilise the potential of Ge nanowires, it is important to explore and understand alternative and functional growth paradigms such as self-seeded nanowire growth, where nanowire growth is usually directed by the in situ-formed catalysts of the growth material, i.e., Ge in this case. Additionally, it is important to understand how the self-seeded nanowires can benefit the device application of nanomaterials as the additional metal seeding can influence electron and phonon transport, and the electronic band structure in the nanomaterials. Here, we review recent advances in the growth and application of self-seeded Ge and Ge-based binary alloy (GeSn) nanowires. Different fabrication methods for growing self-seeded Ge nanowires are delineated and correlated with metal seeded growth. This review also highlights the requirement and advantage of self-seeded growth approach for Ge nanomaterials in the potential applications in energy storage and nanoelectronic devices.
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Affiliation(s)
- Adrià Garcia-Gil
- School of Chemistry, Tyndall National Institute, University College Cork, T12 YN60 Cork, Ireland; (A.G.-G.); (J.D.H.)
- AMBER Centre, Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
| | - Subhajit Biswas
- School of Chemistry, Tyndall National Institute, University College Cork, T12 YN60 Cork, Ireland; (A.G.-G.); (J.D.H.)
- AMBER Centre, Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
| | - Justin D. Holmes
- School of Chemistry, Tyndall National Institute, University College Cork, T12 YN60 Cork, Ireland; (A.G.-G.); (J.D.H.)
- AMBER Centre, Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
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2
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Zhang T, Wang J, Yu L, Xu J, Roca I Cabarrocas P. Advanced radial junction thin film photovoltaics and detectors built on standing silicon nanowires. NANOTECHNOLOGY 2019; 30:302001. [PMID: 30849766 DOI: 10.1088/1361-6528/ab0e57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Three-dimensional (3D) construction of radial junction hydrogenated amorphous silicon (a-Si:H) thin film solar cells on standing silicon nanowires (SiNWs) is a promising strategy to maximize the light harvesting performance and improve the photocarrier collection in an optimized junction configuration. The unique light in-coupling and absorption behaviour in the antenna-like 3D photonic structures also necessitates a set of new theoretical models and simulation tools to design, predict and optimize the photovoltaic performance of radial junction solar cells, which can be rather different from planar junction solar cells. Recently, the performance of radial junction a-Si:H thin film solar cells has progressed steadily to a level comparable or even superior to that of their planar counterparts, with plenty of room for further improvement. This review will first address the growth strategy and critical parameter control of SiNWs produced via a plasma-assisted low-temperature vapour-liquid-solid procedure using low-melting-point metals as the catalyst. Then, the construction of high-performance radial junction thin film solar cells over the standing SiNW matrix, as well as their optimal structural designs, will be introduced. At the end, the new applications of 3D radial junction units will be summarized, which include, for example, the construction of very flexible, low-cost and efficient a-Si:H solar cells with the highest power-to-weight ratio, the demonstration of highly sensitive solar-blind photodetectors operating at the ultraviolet wavelength spectrum and the development of novel biomimetic radial tandem junction photodetectors with an intrinsic red-green-blue (RGB) colour distinguishing capability.
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Affiliation(s)
- Ting Zhang
- National Laboratory of Solid State Microstructures/School of Electronics Science and Engineering, Nanjing University, 210093 Nanjing, People's Republic of China
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3
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Seifner M, Sistani M, Porrati F, Di Prima G, Pertl P, Huth M, Lugstein A, Barth S. Direct Synthesis of Hyperdoped Germanium Nanowires. ACS NANO 2018; 12:1236-1241. [PMID: 29361234 PMCID: PMC5830687 DOI: 10.1021/acsnano.7b07248] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/23/2018] [Indexed: 05/30/2023]
Abstract
A low-temperature chemical vapor growth of Ge nanowires using Ga as seed material is demonstrated. The structural and chemical analysis reveals the homogeneous incorporation of ∼3.5 at. % Ga in the Ge nanowires. The Ga-containing Ge nanowires behave like metallic conductors with a resistivity of about ∼300 μΩcm due to Ga hyperdoping with electronic contributions of one-third of the incorporated Ga atoms. This is the highest conduction value observed by in situ doping of group IV nanowires reported to date. This work demonstrates that Ga is both an efficient seed material at low temperatures for Ge nanowire growth and an effective dopant changing the semiconductor into a metal-like conductor.
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Affiliation(s)
- Michael
S. Seifner
- Institute
of Materials Chemistry, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Masiar Sistani
- Institute
of Solid State Electronics, TU Wien, Floragasse 7, 1040 Vienna, Austria
| | - Fabrizio Porrati
- Physikalisches
Institut, Goethe-Universität, Max-von-Laue-Street 1, 60438 Frankfurt am Main, Germany
| | - Giorgia Di Prima
- Physikalisches
Institut, Goethe-Universität, Max-von-Laue-Street 1, 60438 Frankfurt am Main, Germany
| | - Patrik Pertl
- Institute
of Materials Chemistry, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Michael Huth
- Physikalisches
Institut, Goethe-Universität, Max-von-Laue-Street 1, 60438 Frankfurt am Main, Germany
| | - Alois Lugstein
- Institute
of Solid State Electronics, TU Wien, Floragasse 7, 1040 Vienna, Austria
| | - Sven Barth
- Institute
of Materials Chemistry, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
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4
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Sivaram SV, Hui HY, de la Mata M, Arbiol J, Filler MA. Surface Hydrogen Enables Subeutectic Vapor-Liquid-Solid Semiconductor Nanowire Growth. NANO LETTERS 2016; 16:6717-6723. [PMID: 27347747 DOI: 10.1021/acs.nanolett.6b01640] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Vapor-liquid-solid nanowire growth below the bulk metal-semiconductor eutectic temperature is known for several systems; however, the fundamental processes that govern this behavior are poorly understood. Here, we show that hydrogen atoms adsorbed on the Ge nanowire sidewall enable AuGe catalyst supercooling and control Au transport. Our approach combines in situ infrared spectroscopy to directly and quantitatively determine hydrogen atom coverage with a "regrowth" step that allows catalyst phase to be determined with ex situ electron microscopy. Maintenance of a supercooled catalyst with only hydrogen radical delivery confirms the centrality of sidewall chemistry. This work underscores the importance of the nanowire sidewall and its chemistry on catalyst state, identifies new methods to regulate catalyst composition, and provides synthetic strategies for subeutectic growth in other nanowire systems.
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Affiliation(s)
- Saujan V Sivaram
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Ho Yee Hui
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - María de la Mata
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, Barcelona, Catalonia 08193, Spain
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, Barcelona, Catalonia 08193, Spain
| | - Michael A Filler
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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5
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Chou YC, Panciera F, Reuter MC, Stach EA, Ross FM. Nanowire growth kinetics in aberration corrected environmental transmission electron microscopy. Chem Commun (Camb) 2016; 52:5686-9. [PMID: 27041654 DOI: 10.1039/c6cc00303f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We visualize atomic level dynamics during Si nanowire growth using aberration corrected environmental transmission electron microscopy, and compare with lower pressure results from ultra-high vacuum microscopy. We discuss the importance of higher pressure observations for understanding growth mechanisms and describe protocols to minimize effects of the higher pressure background gas.
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Affiliation(s)
- Yi-Chia Chou
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA and Department of Electrophysics, College of Science, National Chiao Tung University, Hsinchu, Taiwan. and IBM T. J. Watson Research Center, Yorktown Heights, NY, USA.
| | - Federico Panciera
- IBM T. J. Watson Research Center, Yorktown Heights, NY, USA. and Engineering Department, University of Cambridge, Cambridge, UK
| | - Mark C Reuter
- IBM T. J. Watson Research Center, Yorktown Heights, NY, USA.
| | - Eric A Stach
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA
| | - Frances M Ross
- IBM T. J. Watson Research Center, Yorktown Heights, NY, USA.
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6
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Ke Y, Hainey M, Won D, Weng X, Eichfeld SM, Redwing JM. Carrier gas effects on aluminum-catalyzed nanowire growth. NANOTECHNOLOGY 2016; 27:135605. [PMID: 26900836 DOI: 10.1088/0957-4484/27/13/135605] [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
Aluminum-catalyzed silicon nanowire growth under low-pressure chemical vapor deposition conditions requires higher reactor pressures than gold-catalyzed growth, but the reasons for this difference are not well understood. In this study, the effects of reactor pressure and hydrogen partial pressure on silicon nanowire growth using an aluminum catalyst were studied by growing nanowires in hydrogen and hydrogen/nitrogen carrier gas mixtures at different total reactor pressures. Nanowires grown in the nitrogen/hydrogen mixture have faceted catalyst droplet tips, minimal evidence of aluminum diffusion from the tip down the nanowire sidewalls, and significant vapor-solid deposition of silicon on the sidewalls. In comparison, wires grown in pure hydrogen show less well-defined tips, evidence of aluminum diffusion down the nanowire sidewalls at increasing reactor pressures and reduced vapor-solid deposition of silicon on the sidewalls. The results are explained in terms of a model wherein the hydrogen partial pressure plays a critical role in aluminum-catalyzed nanowire growth by controlling hydrogen termination of the silicon nanowire sidewalls. For a given reactor pressure, increased hydrogen partial pressures increase the extent of hydrogen termination of the sidewalls which suppresses SiH4 adsorption thereby reducing vapor-solid deposition of silicon but increases the surface diffusion length of aluminum. Conversely, lower hydrogen partial pressures reduce the hydrogen termination and also increase the extent of SiH4 gas phase decomposition, shifting the nanowire growth window to lower growth temperatures and silane partial pressures.
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Affiliation(s)
- Yue Ke
- Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
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7
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Toan LD, Moyen E, Zamfir MR, Kim YW, Joe J, Lee YH, Pribat D. Connecting wire-based solar cells without any transparent conducting electrode. CrystEngComm 2016. [DOI: 10.1039/c5ce01786f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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He Z, Nguyen HT, Duc Toan L, Pribat D. A detailed study of kinking in indium-catalyzed silicon nanowires. CrystEngComm 2015. [DOI: 10.1039/c5ce00773a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The turning angles of kinked Si nanowires are governed by the different combinations of three types of {111} twins, where TBs are normal to (Twin I), inclined to (Twin II) or parallel to (Twin III) the axes of Si nanowires.
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Affiliation(s)
- Zhanbing He
- State Key Laboratory for Advanced Metals and Materials
- University of Science & Technology Beijing
- Beijing 100083, China
| | - Hung Tran Nguyen
- Department of Energy Science
- Sungkyunkwan University
- Suwon 440-746, Korea
| | - Le Duc Toan
- Department of Energy Science
- Sungkyunkwan University
- Suwon 440-746, Korea
| | - Didier Pribat
- Department of Energy Science
- Sungkyunkwan University
- Suwon 440-746, Korea
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9
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Yu L, Xu M, Xu J, Xue Z, Fan Z, Picardi G, Fortuna F, Wang J, Xu J, Shi Y, Chen K, Roca i Cabarrocas P. In-plane epitaxial growth of silicon nanowires and junction formation on Si(100) substrates. NANO LETTERS 2014; 14:6469-6474. [PMID: 25343717 DOI: 10.1021/nl503001g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Growing self-assembled silicon nanowires (SiNWs) into precise locations represents a critical capability to scale up SiNW-based functionalities. We here report a novel epitaxy growth phenomenon and strategy to fabricate orderly arrays of self-aligned in-plane SiNWs on Si(100) substrates following exactly the underlying crystallographic orientations. We observe also a rich set of distinctive growth dynamics/modes that lead to remarkably different morphologies of epitaxially grown SiNWs/or grains under variant growth balance conditions. High-resolution transmission electron microscopy cross-section analysis confirms a coherent epitaxy (or partial epitaxy) interface between the in-plane SiNWs and the Si(100) substrate, while conductive atomic force microscopy characterization reveals that electrically rectifying p-n junctions are formed between the p-type doped in-plane SiNWs and the n-type c-Si(100) substrate. This in-plane epitaxy growth could provide an effective means to define nanoscale junction and doping profiles, providing a basis for exploring novel nanoelectronics.
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Affiliation(s)
- Linwei Yu
- School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures, Nanjing University , 210093, Nanjing, China
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10
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Dick KA, Caroff P. Metal-seeded growth of III-V semiconductor nanowires: towards gold-free synthesis. NANOSCALE 2014; 6:3006-3021. [PMID: 24522389 DOI: 10.1039/c3nr06692d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Semiconductor nanowires composed of III-V materials have enormous potential to add new functionality to electronics and optical applications. However, integration of these promising structures into applications is severely limited by the current near-universal reliance on gold nanoparticles as seeds for nanowire fabrication. Although highly controlled fabrication is achieved, this metal is entirely incompatible with the Si-based electronics industry. In this Feature we review the progress towards developing gold-free bottom-up synthesis techniques for III-V semiconductor nanowires. Three main categories of nanowire synthesis are discussed: selective-area epitaxy, self-seeding and foreign metal seeding, with main focus on the metal-seeded techniques. For comparison, we also review the development of foreign metal seeded synthesis of silicon and germanium nanowires. Finally, directions for future development and anticipated important trends are discussed. We anticipate significant development in the use of foreign metal seeding in particular. In addition, we speculate that multiple different techniques must be developed in order to replace gold and to provide a variety of nanowire structures and properties suited to a diverse range of applications.
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Affiliation(s)
- Kimberly A Dick
- Solid State Physics, Lund University, S-221 00 Lund, Sweden.
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11
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Wang J, Li X, Gu H. Understanding the Atomic-scale Process of Catalytic Assembly of Si Nanowires through Al Injection. ChemCatChem 2013. [DOI: 10.1002/cctc.201300392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Khayyat MM, Wacaser BA, Reuter MC, Ross FM, Sadana DK, Chen TC. Nanoscale chemical templating of Si nanowires seeded with Al. NANOTECHNOLOGY 2013; 24:235301. [PMID: 23670339 DOI: 10.1088/0957-4484/24/23/235301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We describe a new approach for achieving controlled spatial placement of VLS-grown nanowires that uses an oxygen-reactive seed material and an oxygen-containing mask. Oxygen-reactive seed materials are of great interest for electronic applications, yet they cannot be patterned using the approaches developed for noble metal seed materials such as Au. This new process, nanoscale chemical templating, takes advantage of the reactivity of the blanket seed layer by depositing it over a patterned oxide that reacts with the seed material to prevent nanowire growth in undesired locations. Here we demonstrate this technique using Al as the seed material and SiO2 as the mask, and we propose that this methodology will be applicable to other reactive metals that are of interest for nanowire growth. The method has other advantages over conventional patterning approaches for certain applications including reducing patterning steps, flexibility in lithographic techniques, and high growth yields. We demonstrate its application with standard and microsphere lithography. We show a high growth yield and fidelity, with no NWs between openings and a majority of openings occupied by a single vertical nanowire, and discuss the dependence of yield on parameters.
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Affiliation(s)
- Maha M Khayyat
- King Abdul Aziz City for Science and Technology, Riyadh, 11442, Kingdom of Saudi Arabia
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13
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Moutanabbir O, Isheim D, Blumtritt H, Senz S, Pippel E, Seidman DN. Colossal injection of catalyst atoms into silicon nanowires. Nature 2013; 496:78-82. [DOI: 10.1038/nature11999] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 02/07/2013] [Indexed: 11/09/2022]
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14
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Hillerich K, Dick KA, Wen CY, Reuter MC, Kodambaka S, Ross FM. Strategies to control morphology in hybrid group III-V/group IV heterostructure nanowires. NANO LETTERS 2013; 13:903-908. [PMID: 23421434 DOI: 10.1021/nl303660h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
By combining in situ and ex situ transmission electron microscopy measurements, we examine the factors that control the morphology of "hybrid" nanowires that include group III-V and group IV materials. We focus on one materials pair, GaP/Si, for which we use a wide range of growth parameters. We show through video imaging that nanowire morphology depends on growth conditions, but that a general pattern emerges where either single kinks or inclined defects form some distance after the heterointerface. We show that pure Si nanowires can be made to exhibit the same kinks and defects by changing their droplet volume. From this we derive a model where droplet geometry drives growth morphology and discuss optimization strategies. We finally discuss morphology control for material pairs where the second material kinks immediately at the heterointerface and show that an interlayer between segments can enable the growth of unkinked hybrid nanowires.
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Affiliation(s)
- Karla Hillerich
- Solid State Physics, Lund University, Box 118, S-221 00 Lund, Sweden
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15
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Chou YC, Wen CY, Reuter MC, Su D, Stach EA, Ross FM. Controlling the growth of Si/Ge nanowires and heterojunctions using silver-gold alloy catalysts. ACS NANO 2012; 6:6407-6415. [PMID: 22708581 DOI: 10.1021/nn301978x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We describe a new catalyst for group IV nanowire heterostructures, based on alloying Ag with Au, that combines the ability to control catalyst phase and nanowire structure with good environmental stability. Compared to other alloy catalysts, we show a higher oxidation resistance of AgAu and more consistent crystal shapes and catalyst/nanowire orientation relationships during growth. We show that AgAu catalysts are also stable against diffusion during growth, making them capable of forming long nanowires with uniform diameters. Furthermore, we demonstrate the growth of compositionally abrupt Si/Ge heterojunctions with good reproducibility and yield, switching individual nanowires between vapor-liquid-solid and vapor-solid-solid growth to optimize growth rates by control of the catalyst state. The stability and properties of AgAu catalysts potentially open up a promising and practical route toward control of group IV heterostructure nanowires.
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Affiliation(s)
- Yi-Chia Chou
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
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16
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Kallesøe C, Wen CY, Booth TJ, Hansen O, Bøggild P, Ross FM, Mølhave K. In situ TEM creation and electrical characterization of nanowire devices. NANO LETTERS 2012; 12:2965-2970. [PMID: 22545629 DOI: 10.1021/nl300704u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrate the observation and measurement of simple nanoscale devices over their complete lifecycle from creation to failure within a transmission electron microscope. Devices were formed by growing Si nanowires, using the vapor-liquid-solid method, to form bridges between Si cantilevers. We characterize the formation of the contact between the nanowire and the cantilever, showing that the nature of the connection depends on the flow of heat and electrical current during and after the moment of contact. We measure the electrical properties and high current failure characteristics of the resulting bridge devices in situ and relate these to the structure. We also describe processes to modify the contact and the nanowire surface after device formation. The technique we describe allows the direct analysis of the processes taking place during device formation and use, correlating specific nanoscale structural and electrical parameters on an individual device basis.
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Affiliation(s)
- Christian Kallesøe
- Department of Micro- and Nanotechnology, Technical University of Denmark, Kgs. Lyngby, Denmark
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17
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Eichfeld CM, Gerstl SSA, Prosa T, Ke Y, Redwing JM, Mohney SE. Local electrode atom probe analysis of silicon nanowires grown with an aluminum catalyst. NANOTECHNOLOGY 2012; 23:215205. [PMID: 22552162 DOI: 10.1088/0957-4484/23/21/215205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Local electrode atom probe (LEAP) tomography of Al-catalyzed silicon nanowires synthesized by the vapor–liquid–solid method is presented. The concentration of Al within the Al-catalyzed nanowire was found to be 2 × 10(20) cm(-3), which is higher than the expected solubility limit for Al in Si at the nanowire growth temperature of 550°C. Reconstructions of the Al contained within the nanowire indicate a denuded region adjacent to the Al catalyst/Si nanowire interface, while Al clusters are distributed throughout the rest of the silicon nanowire.
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Affiliation(s)
- Chad M Eichfeld
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
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18
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Wang GG, Zhu LQ, Liu HC, Li WP. Self-assembled biomimetic superhydrophobic CaCO3 coating inspired from fouling mineralization in geothermal water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:12275-12279. [PMID: 21919516 DOI: 10.1021/la202613r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Inspired from fouling self-mineralization in geothermal water, a novel biomimetic cactuslike CaCO(3) coating with superhydrophobic features is reported in this letter. The structure, morphologies, and phases of the CaCO(3) coating were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, and infrared spectrophotometry. After prenucleation treatment, a continuous cactuslike CaCO(3) coating with hierarchical nano- and microstructures was self-assembled on stainless steel surfaces after immersion in simulated geothermal water at 50 °C for 48 h. After being modified with a low-surface-energy monolayer of sodium stearate, the as-prepared coating exhibited superhydrophobic properties with a water contact angle of 158.9° and a sliding angle of 2°. Therefore, this work might open up a new application field of geothermal resources and provide insight into designing multidimensional structures with functional applications, including superhydrophobic surfaces.
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Affiliation(s)
- Gong G Wang
- Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191, China
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19
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Bryce BA, Reuter MC, Wacaser BA, Tiwari S. Contactless measurement of surface dominated recombination in gold- and aluminum-catalyzed silicon vapor-liquid-solid wires. NANO LETTERS 2011; 11:4282-4287. [PMID: 21939179 DOI: 10.1021/nl202279z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Carrier lifetimes of Si micro/nanowires grown by the vapor-liquid-solid method are measured using an extension of the classic contactless photoconductivity decay method. The samples measured consist of a thin aggregated film of oxide passivated wires on a fused silica carrier. Au catalyzed wires in the 392-730 nm diameter range are studied. Recombination in these wires is controlled by the surface or near surface effects, not bulk Au impurities. The lifetimes of Au- and Al-catalyzed wires of comparable diameter are measured. The Al wires are found to have slightly longer lifetimes than those grown with Au at a comparable diameter. Across all samples, the lifetimes measured range was from 0.2 to 1.0 ns. The surface controlled nature of the recombination measured implies larger diameter wires will offer better performance in devices that rely on minority carrier transport.
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Affiliation(s)
- Brian A Bryce
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.
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20
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Chang CC, Chen H, Chen CC, Hung WH, Hsu IK, Theiss J, Zhou C, Cronin SB. Tailoring the crystal structure of individual silicon nanowires by polarized laser annealing. NANOTECHNOLOGY 2011; 22:305709. [PMID: 21719968 DOI: 10.1088/0957-4484/22/30/305709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the effect of polarized laser annealing on the crystalline structure of individual crystalline-amorphous core-shell silicon nanowires (NWs) using Raman spectroscopy. The crystalline fraction of the annealed spot increases dramatically from 0 to 0.93 with increasing incident laser power. We observe Raman lineshape narrowing and frequency hardening upon laser annealing due to the growth of the crystalline core, which is confirmed by high resolution transmission electron microscopy (HRTEM). The anti-Stokes:Stokes Raman intensity ratio is used to determine the local heating temperature caused by the intense focused laser, which exhibits a strong polarization dependence in Si NWs. The most efficient annealing occurs when the laser polarization is aligned along the axis of the NWs, which results in an amorphous-crystalline interface less than 0.5 µm in length. This paper demonstrates a new approach to control the crystal structure of NWs on the sub-micron length scale.
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Affiliation(s)
- Chia-Chi Chang
- Department of Physics, University of Southern California, Los Angeles, CA 90089, USA
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21
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Wen CY, Tersoff J, Hillerich K, Reuter MC, Park JH, Kodambaka S, Stach EA, Ross FM. Periodically changing morphology of the growth interface in Si, Ge, and GaP nanowires. PHYSICAL REVIEW LETTERS 2011; 107:025503. [PMID: 21797618 DOI: 10.1103/physrevlett.107.025503] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 04/20/2011] [Indexed: 05/26/2023]
Abstract
Nanowire growth in the standard <111> direction is assumed to occur at a planar catalyst-nanowire interface, but recent reports contradict this picture. Here we show that a nonplanar growth interface is, in fact, a general phenomenon. Both III-V and group IV nanowires show a distinct region at the trijunction with a different orientation whose size oscillates during growth, synchronized with step flow. We develop an explicit model for this structure that agrees well with experiment and shows that the oscillations provide a direct visualization of catalyst supersaturation. We discuss the implications for wire growth and structure.
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Affiliation(s)
- C-Y Wen
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
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22
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Moutanabbir O, Senz S, Scholz R, Alexe M, Kim Y, Pippel E, Wang Y, Wiethoff C, Nabbefeld T, Meyer zu Heringdorf F, Horn-von Hoegen M. Atomically smooth p-doped silicon nanowires catalyzed by aluminum at low temperature. ACS NANO 2011; 5:1313-1320. [PMID: 21210666 DOI: 10.1021/nn1030274] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Silicon nanowires (SiNWs) are powerful nanotechnological building blocks. To date, a variety of metals have been used to synthesize high-density epitaxial SiNWs through metal-catalyzed vapor phase epitaxy. Understanding the impact of the catalyst on the intrinsic properties of SiNWs is critical for precise manipulation of the emerging SiNW-based devices. Here we demonstrate that SiNWs synthesized at low-temperature by ultrahigh vacuum chemical vapor deposition using Al as a catalyst present distinct morphological properties. In particular, these nanowires are atomically smooth in contrast to rough {112}-type sidewalls characteristic of the intensively investigated Au-catalyzed SiNWs. We show that the stabilizing effect of Al plays the key role in the observed nanowire surface morphology. In fact, unlike Au which induces (111) and (113) facets on the nanowire sidewall surface, Al revokes the reconstruction along the [112] direction leading to equivalent adjacent step edges and flat surfaces. Our finding sets the lower limit of the Al surface density on the nanowire sidewalls at ∼2 atom/nm(2). Additionally, despite using temperatures of ca. 110-170 K below the eutectic point, we found that the incorporation of Al into the growing nanowires is sufficient to induce an effective p-type doping of SiNWs. These results demonstrate that the catalyst plays a crucial role is shaping the structural and electrical properties of SiNWs.
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Affiliation(s)
- Oussama Moutanabbir
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Saale), Germany
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23
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Peng KQ, Lee ST. Silicon nanowires for photovoltaic solar energy conversion. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:198-215. [PMID: 20931630 DOI: 10.1002/adma.201002410] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Semiconductor nanowires are attracting intense interest as a promising material for solar energy conversion for the new-generation photovoltaic (PV) technology. In particular, silicon nanowires (SiNWs) are under active investigation for PV applications because they offer novel approaches for solar-to-electric energy conversion leading to high-efficiency devices via simple manufacturing. This article reviews the recent developments in the utilization of SiNWs for PV applications, the relationship between SiNW-based PV device structure and performance, and the challenges to obtaining high-performance cost-effective solar cells.
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Affiliation(s)
- Kui-Qing Peng
- Department of Physics, Beijing Normal University, Beijing 100875, P. R. China
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24
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Yuan FW, Yang HJ, Tuan HY. Seeded silicon nanowire growth catalyzed by commercially available bulk metals: broad selection of metal catalysts, superior field emission performance, and versatile nanowire/metal architectures. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11956g] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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25
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Wen CY, Tersoff J, Reuter MC, Stach EA, Ross FM. Step-flow kinetics in nanowire growth. PHYSICAL REVIEW LETTERS 2010; 105:195502. [PMID: 21231182 DOI: 10.1103/physrevlett.105.195502] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Indexed: 05/28/2023]
Abstract
Nanowire growth occurs by step flow at the wire-catalyst interface, with strikingly different step-flow kinetics for solid versus liquid catalysts. Here we report quantitative in situ measurements of step flow together with a kinetic model that reproduces the behavior. This allows us to identify the key parameters controlling step-flow growth, evaluate changes in the catalyst composition during growth, and identify the most favorable conditions for growing abrupt heterojunctions in nanowires.
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Affiliation(s)
- C-Y Wen
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA
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26
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Gamalski AD, Tersoff J, Sharma R, Ducati C, Hofmann S. Formation of metastable liquid catalyst during subeutectic growth of germanium nanowires. NANO LETTERS 2010; 10:2972-2976. [PMID: 20608714 DOI: 10.1021/nl101349e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Lattice-resolved, video-rate environmental transmission electron microscopy shows the formation of a liquid Au-Ge layer on sub-30-nm Au catalyst crystals and the transition of this two-phase Au-Ge/Au coexistence to a completely liquid Au-Ge droplet during isothermal digermane exposure at temperatures far below the bulk Au-Ge eutectic temperature. Upon Ge crystal nucleation and subsequent Ge nanowire growth, the catalyst either recrystallizes or remains liquid, apparently stabilized by the Ge supersaturation. We argue that there is a large energy barrier to nucleate diamond-cubic Ge, but not to nucleate the Au-Ge liquid. As a result, the system follows the more kinetically accessible path, forming a liquid even at 240 degrees C, although there is no liquid along the most thermodynamically favorable path below 360 degrees C.
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Affiliation(s)
- A D Gamalski
- Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK
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27
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Wen CY, Reuter MC, Tersoff J, Stach EA, Ross FM. Structure, growth kinetics, and ledge flow during vapor-solid-solid growth of copper-catalyzed silicon nanowires. NANO LETTERS 2010; 10:514-519. [PMID: 20041666 DOI: 10.1021/nl903362y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We use real-time observations of the growth of copper-catalyzed silicon nanowires to determine the nanowire growth mechanism directly and to quantify the growth kinetics of individual wires. Nanowires were grown in a transmission electron microscope using chemical vapor deposition on a copper-coated Si substrate. We show that the initial reaction is the formation of a silicide, eta'-Cu(3)Si, and that this solid silicide remains on the wire tips during growth so that growth is by the vapor-solid-solid mechanism. Individual wire directions and growth rates are related to the details of orientation relation and catalyst shape, leading to a rich morphology compared to vapor-liquid-solid grown nanowires. Furthermore, growth occurs by ledge propagation at the silicide/silicon interface, and the ledge propagation kinetics suggest that the solubility of precursor atoms in the catalyst is small, which is relevant to the fabrication of abrupt heterojunctions in nanowires.
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Affiliation(s)
- C-Y Wen
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
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28
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Schmidt V, Wittemann JV, Gösele U. Growth, Thermodynamics, and Electrical Properties of Silicon Nanowires. Chem Rev 2010; 110:361-88. [DOI: 10.1021/cr900141g] [Citation(s) in RCA: 427] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Schmidt
- Max Planck Institute of Microstructure Physics, Halle, Germany, and School of Engineering, Duke University, Durham, North Carolina
| | - J. V. Wittemann
- Max Planck Institute of Microstructure Physics, Halle, Germany, and School of Engineering, Duke University, Durham, North Carolina
| | - U. Gösele
- Max Planck Institute of Microstructure Physics, Halle, Germany, and School of Engineering, Duke University, Durham, North Carolina
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29
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Wen CY, Reuter MC, Bruley J, Tersoff J, Kodambaka S, Stach EA, Ross FM. Formation of Compositionally Abrupt Axial Heterojunctions in Silicon-Germanium Nanowires. Science 2009; 326:1247-50. [DOI: 10.1126/science.1178606] [Citation(s) in RCA: 282] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We have formed compositionally abrupt interfaces in silicon-germanium (Si-Ge) and Si-SiGe heterostructure nanowires by using solid aluminum-gold alloy catalyst particles rather than the conventional liquid semiconductor–metal eutectic droplets. We demonstrated single interfaces that are defect-free and close to atomically abrupt, as well as quantum dots (i.e., Ge layers tens of atomic planes thick) embedded within Si wires. Real-time imaging of growth kinetics reveals that a low solubility of Si and Ge in the solid particle accounts for the interfacial abruptness. Solid catalysts that can form functional group IV nanowire-based structures may yield an extended range of electronic applications.
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