201
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Petersen EW, Likovich EM, Russell KJ, Narayanamurti V. Growth of ZnO nanowires catalyzed by size-dependent melting of Au nanoparticles. NANOTECHNOLOGY 2009; 20:405603. [PMID: 19738315 DOI: 10.1088/0957-4484/20/40/405603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a general approach to growing ZnO nanowires on arbitrary, high melting point (above 970 degrees C) substrates using the vapor-liquid-solid (VLS) growth mechanism. Our approach utilizes the melting point reduction of sufficiently small (5 nm diameter) Au particles to provide a liquid catalyst without substrate interaction. Using this size-dependent melting effect, we demonstrate catalytic VLS growth of ZnO nanowires on both Ti and Mo foil substrates with aspect ratios in excess of 1000:1. Transmission electron microscopy shows the nanowires to be single-crystalline, and photoluminescence spectra show high-quality optical properties. We believe this growth technique to be widely applicable to a variety of substrates and material systems.
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Affiliation(s)
- Eric W Petersen
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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202
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Hu S, Leu PW, Marshall AF, McIntyre PC. Single-crystal germanium layers grown on silicon by nanowire seeding. NATURE NANOTECHNOLOGY 2009; 4:649-653. [PMID: 19809455 DOI: 10.1038/nnano.2009.233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 07/14/2009] [Indexed: 05/28/2023]
Abstract
Three-dimensional integration and the combination of different material systems are central themes of electronics research. Recently, as-grown vertical one-dimensional structures have been integrated into high-density three-dimensional circuits. However, little attention has been paid to the unique structural properties of germanium nanowires obtained by epitaxial and heteroepitaxial growth on Ge(111) and Si(111) substrates, despite the fact that the integration of germanium on silicon is attractive for device applications. Here, we demonstrate the lateral growth of single crystal germanium islands tens of micrometres in diameter by seeding from germanium nanowires grown on a silicon substrate. Vertically aligned high-aspect-ratio nanowires can transfer the orientation and perfection of the substrate crystal to overlying layers a micrometre or more above the substrate surface. This technique can be repeated to build multiple active device layers, a key requirement for the fabrication of densely interconnected three-dimensional integrated circuits.
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Affiliation(s)
- Shu Hu
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
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203
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Kirmse H, Häusler I, Kret S, Janik E, Karczewski G, Wojtowicz T. TEM analysis of the container effect of Au-based catalyst droplets during vapour-liquid-solid growth of axial ZnTe/CdTe nanowires. CRYSTAL RESEARCH AND TECHNOLOGY 2009. [DOI: 10.1002/crat.200900475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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204
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Wacaser BA, Reuter MC, Khayyat MM, Wen CY, Haight R, Guha S, Ross FM. Growth system, structure, and doping of aluminum-seeded epitaxial silicon nanowires. NANO LETTERS 2009; 9:3296-3301. [PMID: 19639967 DOI: 10.1021/nl9015792] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have examined the formation of silicon nanowires grown by self-assembly from Si substrates with thin aluminum films. Postgrowth and in situ investigations using various Al deposition and annealing conditions suggest that nanowire growth takes place with a supercooled liquid droplet (i.e., the vapor-liquid-solid system), even though the growth temperatures are below the bulk Al/Si eutectic temperature. Wire morphology as a function of processing conditions is also described. It is shown that when Al environmental exposure is prevented before wire growth a wide process window for wire formation can be achieved. Under optimum growth conditions, it is possible to produce excellent crystal quality nanowires with rapid growth rates, high surface densities, low diameter dispersion, and controlled tapering. Photoelectron spectroscopy measurements indicate that the use of Al leads to active doping levels that depend on the growth temperature in as-grown nanowires and increase when annealed. We suggest that these structural and electronic properties will be relevant to photovoltaic and other applications, where the more common use of Au is believed to be detrimental to performance.
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Affiliation(s)
- Brent A Wacaser
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA.
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205
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Tizei LHG, Chiaramonte T, Ugarte D, Cotta MA. III-V semiconductor nanowire growth: does arsenic diffuse through the metal nanoparticle catalyst? NANOTECHNOLOGY 2009; 20:275604. [PMID: 19531855 DOI: 10.1088/0957-4484/20/27/275604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The synthesis of III-V semiconductor nanowires (NWs) is based on the delivery of atoms from a vapor phase to a catalytic metal nanoparticle (NP). Although there has been extensive work on such systems, the incorporation pathways of group V atoms remain an open issue. Here, we have performed a detailed structural and chemical analysis of the catalyst NP in NWs where we switch the V atomic element during growth (heterostructured InP/InAs/InP NWs). Our experimental results indicate a group V pathway where these atoms actually diffuse through the catalytic NP by formation of a stable phase containing As under growth conditions. We have observed distinct NW growth behavior within a narrow temperature range (30 degrees C) suggesting a transition between vapor-liquid-solid and vapor-solid-solid growth modes.
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Affiliation(s)
- L H G Tizei
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, C P 6165,13083-970 Campinas, SP, Brazil.
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206
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Hwang IC, Kumar R, Kim ND, Chun Y, Lee JW, Kumar P, Mana RS, Choi C, Lee JR, Kim KS. Controlling metal nanotoppings on the tip of silicide nanostructures. NANOTECHNOLOGY 2009; 20:245605. [PMID: 19471081 DOI: 10.1088/0957-4484/20/24/245605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Utilizing the difference in surface tension between SiO2 and metal catalysts (Mn2+, Ni2+), we show how metals form nanoshells, nanodiscs and nanospheres at the tips of the SiO2 nanostructures of nanocones, nanorods and nanowires. For the Mn2+ catalyst (i), SiO2-nanocones are formed with the hemispherical convex cap of the MnO/SiO2 composite. For the Ni2+ catalyst (ii), SiO2 nanowires are grown due to the concave shape of SiO2 surrounding the multi-faceted NiSi particles at their tip. For the Mn2+/Ni2+ catalyst (iii), SiO2 nanorods are formed with large-sized spherical ferromagnetic single Ni nanocrystals (50-200 nm in diameter) surrounded by the concave MnO2/SiO2 composite at the tip of the SiO2 nanorods. This large-sized spherical formation of the single Ni crystal is possible because Ni is able to be chemically reduced by Mn at 950 degrees C, well below the melting point of Ni (1455 degrees C) due to the alloying effect.
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Affiliation(s)
- In Chul Hwang
- Department of Chemistry, Center for Superfunctional Materials, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea
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207
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Gao L, Woo RL, Liang B, Pozuelo M, Prikhodko S, Jackson M, Goel N, Hudait MK, Huffaker DL, Goorsky MS, Kodambaka S, Hicks RF. Self-catalyzed epitaxial growth of vertical indium phosphide nanowires on silicon. NANO LETTERS 2009; 9:2223-2228. [PMID: 19413340 DOI: 10.1021/nl803567v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Vertical indium phosphide nanowires have been grown epitaxially on silicon (111) by metalorganic vapor-phase epitaxy. Liquid indium droplets were formed in situ and used to catalyze deposition. For growth at 350 degrees C, about 70% of the wires were vertical, while the remaining ones were distributed in the 3 other <111> directions. The vertical fraction, growth rate, and tapering of the wires increased with temperature and V/III ratio. At 370 degrees C and V/III equal to 200, 100% of the wires were vertical with a density of approximately 1.0 x 10(9) cm(-2) and average dimensions of 3.9 mum in length, 45 nm in base width, and 15 nm in tip width. X-ray diffraction and transmission electron microscopy revealed that the wires were single-crystal zinc blende, although they contained a high density of rotational twins perpendicular to the <111> growth direction. The room temperature photoluminescence spectrum exhibited one peak centered at 912 +/- 10 nm with a FWHM of approximately 60 nm.
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Affiliation(s)
- Li Gao
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
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208
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Woo RL, Gao L, Goel N, Hudait MK, Wang KL, Kodambaka S, Hicks RF. Kinetic control of self-catalyzed indium phosphide nanowires, nanocones, and nanopillars. NANO LETTERS 2009; 9:2207-2211. [PMID: 19419156 DOI: 10.1021/nl803584u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The morphological phase diagram is reported for InP nanostructures grown on InP (111)B as a function of temperature and V/III ratio. Indium droplets were used as the catalyst and were generated in situ in the metalorganic vapor-phase epitaxy reactor. Three distinct nanostructures were observed: wires, cones, and pillars. It is proposed that the shape depends on the relative rates of indium phosphide deposition via the vapor-liquid-solid (VLS) and vapor-phase epitaxy (VPE) processes. The rate of VLS is relatively insensitive to temperature and results in vertical wire growth starting at 350 degrees C. By contrast, the rate of VPE accelerates with temperature and drives the lateral growth of cones at 385 degrees C and then pillars at 400 degrees C.
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Affiliation(s)
- Robyn L Woo
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA
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209
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Li J, Wang LS, Buchholz DB, Chang RPH. Simultaneous growth of pure hyperbranched Zn3As2 structures and long Ga2O3 nanowires. NANO LETTERS 2009; 9:1764-1769. [PMID: 19331337 DOI: 10.1021/nl8035228] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Through a facile and highly repeatable chemical vapor method, pure three-dimensional hyperbranched Zn(3)As(2) structures and ultralong Ga(2)O(3) nanowires were simultaneously grown with controllable locations in the same experiment. The hyperbranched Zn(3)As(2) consists of cone-shaped submicro-/nanowires and has a single-crystalline tetragonal structure. This is the first report of nano Zn(3)As(2) and hyperbranched Zn(3)As(2) structures. The as-grown Ga(2)O(3) nanowires are monoclinic single crystals. A vapor-solid-solid mechanism is suggested for the growth of the Ga(2)O(3) nanowires, and a vapor-solid mechanism, for the Zn(3)As(2) structures.
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Affiliation(s)
- Jianye Li
- Department of Materials Science & Engineering and Materials Research Center, Northwestern University, Evanston, Illinois 60208, USA.
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210
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Wang Q, Chen G, Zhou N. The large-scale synthesis and growth mechanism of II-B metal nanosponges through a vacuum vapor deposition route. NANOTECHNOLOGY 2009; 20:085602. [PMID: 19417450 DOI: 10.1088/0957-4484/20/8/085602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
By carefully controlling the experimental parameters, large-scale nanosponges of group II-B metal (Zn and Cd) on Si substrates are fabricated through a vacuum vapor deposition route (VVD). The as-prepared products are systematically characterized by the techniques of powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is shown that nanosponges are composed of network nanowires, which are 20-250 nm in diameter and hundreds of micrometers in length. On the basis of the time-dependent experimental findings, the nucleation and growth of the nanowires have been elucidated. Moreover, the melting behavior of a single ultrathin zinc nanowire was observed in situ under the irradiation of an electron beam during the TEM measurement for the first time, showing that the melting point of the ultrathin zinc nanowire is significantly lower than that of the bulk.
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Affiliation(s)
- Qun Wang
- Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001, People's Republic of China
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211
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Weng X, Burke RA, Redwing JM. The nature of catalyst particles and growth mechanisms of GaN nanowires grown by Ni-assisted metal-organic chemical vapor deposition. NANOTECHNOLOGY 2009; 20:085610. [PMID: 19417458 DOI: 10.1088/0957-4484/20/8/085610] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The structure and chemistry of the catalyst particles that terminate GaN nanowires grown by Ni-assisted metal-organic chemical vapor deposition were investigated using a combination of electron diffraction, high-resolution transmission electron microscopy, and x-ray energy dispersive spectrometry. The crystal symmetry, lattice parameter, and chemical composition obtained reveal that the catalyst particles are Ni(3)Ga with an ordered L 1(2) structure. The results suggest that the catalyst is a solid particle during growth and therefore favor a vapor-solid-solid mechanism for the growth of GaN nanowires under these conditions.
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Affiliation(s)
- Xiaojun Weng
- Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA
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212
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Drínek V, Subrt J, Klementová M, Rieder M, Fajgar R. From shelled Ge nanowires to SiC nanotubes. NANOTECHNOLOGY 2009; 20:035606. [PMID: 19417301 DOI: 10.1088/0957-4484/20/3/035606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Shelled germanium nanowires up to 100 nm in diameter and several micrometers in length were prepared by low pressure chemical vapor deposition (LPCVD) of tris(trimethylsilyl)germane (SiMe(3))(3)GeH. Vapors of the precursor were deposited on tantalum substrates in an oven at 365 degrees C. Subsequently, the products were annealed at 700 degrees C in vacuum. The wires consist of a crystalline Ge core surrounded by a two-layer jacket. The presence of hexagonal Ge in the core was documented in some of the nanowires. The inner jacket is formed by amorphous germanium, the outer part by an Si/C material. By annealing at 900 degrees C, germanium in the core is expelled and nanotubes formed by the Si/C material remain. The samples were studied by SEM, HRTEM, EDX, FTIR and Raman spectroscopy, and the XRD technique.
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Affiliation(s)
- Vladislav Drínek
- Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135,165 02 Prague 6, Czech Republic.
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213
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Chu WG, Wang HF, Guo YJ, Zhang LN, Han ZH, Li QQ, Fan SS. Catalyst-Free Growth of Quasi-Aligned Nanorods of Single Crystal Cu3Mo2O9 and Their Catalytic Properties. Inorg Chem 2009; 48:1243-9. [DOI: 10.1021/ic801885c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W. G. Chu
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - H. F. Wang
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - Y. J. Guo
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - L. N. Zhang
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - Z. H. Han
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - Q. Q. Li
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
| | - S. S. Fan
- National Center for Nanoscience and Technology of China, Beijing 100085, P. R. China, Tsinghua-Foxconn Nanotechnology Research Center, Tsinghua University, Beijing 100085, P. R. China, and Department of Physics, Tsinghua University, Beijing 100085, P. R. China
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214
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Pei LZ, Zhao HS, Tan W, Yu HY, Chen YW, Zhang QF, Fan CG. Low temperature growth and characterizations of single crystalline CuGeO3 nanowires. CrystEngComm 2009. [DOI: 10.1039/b900837n] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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215
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Heo K, Kim CJ, Jo MH, Hong S. Massive integration of inorganic nanowire-based structures on solid substrates for device applications. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b817136j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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216
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Lensch-Falk JL, Hemesath ER, Perea DE, Lauhon LJ. Alternative catalysts for VSS growth of silicon and germanium nanowires. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b817391e] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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217
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Prikhodko S, Sitzman S, Gambin V, Kodambaka S. In situ electron backscattered diffraction of individual GaAs nanowires. Ultramicroscopy 2008; 109:133-8. [DOI: 10.1016/j.ultramic.2008.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 07/11/2008] [Accepted: 09/12/2008] [Indexed: 10/21/2022]
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218
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Abstract
For the first time, the growth of ZnO nanobelts was monitored in situ using x-ray diffraction. The growth was carried out by heating metallic zinc powder in air at temperatures ranging from 368 to 568 °C. The morphology depends on both the growth temperature and the rate of heating to that temperature. A morphology diagram for the synthesized products was generated after systematic study of the experimental parameters. Higher temperatures and faster heating rates favor one-dimensional growth. Faster growth was observed for samples with higher growth temperatures, lower heating rates, and one-dimensional growth. These results give insight into the mechanism for the growth of ZnO nanobelts by metal oxidation.
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Affiliation(s)
- Melanie Kirkham
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245, USA
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219
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Schwalbach EJ, Voorhees PW. Phase equilibrium and nucleation in VLS-grown nanowires. NANO LETTERS 2008; 8:3739-3745. [PMID: 18954122 DOI: 10.1021/nl801987j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Phase diagrams accounting for capillarity and surface stress in VLS-grown nanowires have been calculated, and linearized forms for the compositions of the solid and liquid are given. The solid-vapor interfacial energy causes a significant depression of the liquidus, and the impurity concentration in the wire decreases with decreasing wire diameter. Nucleation calculations give upper bounds on the nucleation temperature and liquid supersaturation during growth that are consistent with measurements in the Au-Ge system.
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Affiliation(s)
- Edwin J Schwalbach
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
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220
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Kim DS, Scholz R, Gösele U, Zacharias M. Gold at the root or at the tip of ZnO nanowires: a model. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2008; 4:1615-1619. [PMID: 18770505 DOI: 10.1002/smll.200800060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Dong Sik Kim
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
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221
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Wang SL, He YH, Zou J, Wang Y, Huang H, Huang BY, Liu CT, Liaw PK. Catalytic growth of metallic tungsten whiskers based on the vapor-solid-solid mechanism. NANOTECHNOLOGY 2008; 19:345604. [PMID: 21730653 DOI: 10.1088/0957-4484/19/34/345604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Metallic W whiskers with tip diameters of 50-250 nm and lengths of 2-4 µm have been successfully synthesized in large quantities using Co-Ni alloyed catalysts. The relatively low growth temperature of 850 °C and the large catalyst size (over 100 nm) suggest that the growth of the W whiskers must be governed by the vapor-solid-solid mechanism. Our results show that the vapor-solid-solid model is suitable not only for the growth of nano-scaled whiskers with diameters below 100 nm, but also for submicro-scaled whiskers with diameters well above 100 nm. This technique has great potential to synthesize well controlled metallic whiskers.
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Affiliation(s)
- S L Wang
- State Key Laboratory for Powder Metallurgy, School of Physics Science and Technology, Central South University, Changsha 410083, People's Republic of China. Key Laboratory of Low Dimensional Materials and Application Technology (Xiangtan University), Ministry of Education, Xiangtan 411005, People's Republic of China
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222
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Wang H, Zhang ZP, Wang XN, Mo Q, Wang Y, Zhu JH, Wang HB, Yang FJ, Jiang Y. Selective Growth of Vertical-aligned ZnO Nanorod Arrays on Si Substrate by Catalyst-free Thermal Evaporation. NANOSCALE RESEARCH LETTERS 2008; 3:309. [PMCID: PMC3244890 DOI: 10.1007/s11671-008-9156-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 08/05/2008] [Indexed: 05/29/2023]
Abstract
By thermal evaporation of pure ZnO powders, high-density vertical-aligned ZnO nanorod arrays with diameter ranged in 80–250 nm were successfully synthesized on Si substrates covered with ZnO seed layers. It was revealed that the morphology, orientation, crystal, and optical quality of the ZnO nanorod arrays highly depend on the crystal quality of ZnO seed layers, which was confirmed by the characterizations of field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and photoluminescence measurements. For ZnO seed layer with wurtzite structure, the ZnO nanorods grew exactly normal to the substrate with perfect wurtzite structure, strong near-band-edge emission, and neglectable deep-level emission. The nanorods synthesized on the polycrystalline ZnO seed layer presented random orientation, wide diameter, and weak deep-level emission. This article provides a C-free and Au-free method for large-scale synthesis of vertical-aligned ZnO nanorod arrays by controlling the crystal quality of the seed layer.
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Affiliation(s)
- H Wang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - ZP Zhang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - XN Wang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - Q Mo
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - Y Wang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - JH Zhu
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - HB Wang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - FJ Yang
- Faculty of Physics and Electronic Technology, Hubei University, Wuhan, 430062, People’s Republic of China
| | - Y Jiang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
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223
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Yoshida H, Takeda S, Uchiyama T, Kohno H, Homma Y. Atomic-scale in-situ observation of carbon nanotube growth from solid state iron carbide nanoparticles. NANO LETTERS 2008; 8:2082-6. [PMID: 18505300 DOI: 10.1021/nl080452q] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We have first observed the nucleation and growth process of carbon nanotubes (CNTs) from iron carbide (Fe 3C) nanoparticles in chemical vapor deposition with C 2H 2 by in situ environmental transmission electron microscopy. Graphitic networks are formed on the fluctuating iron carbide nanoparticles, and subsequently CNTs are expelled from them. Our atomic scale observations suggest that carbon atoms diffuse through the bulk of iron carbide nanoparticles during the growth of CNTs.
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Affiliation(s)
- Hideto Yoshida
- Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043, Japan
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224
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Caroff P, Wagner JB, Dick KA, Nilsson HA, Jeppsson M, Deppert K, Samuelson L, Wallenberg LR, Wernersson LE. High-quality InAs/InSb nanowire heterostructures grown by metal-organic vapor-phase epitaxy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2008; 4:878-882. [PMID: 18576282 DOI: 10.1002/smll.200700892] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Philippe Caroff
- Solid State Physics/The Nanometer Structure Consortium, Lund University, Box 118 SE-22100 Lund, Sweden.
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225
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Recognition of melting of nanoparticle catalysts with cubically shaped Co3O4 nanoparticles. J Colloid Interface Sci 2008; 321:251-5. [DOI: 10.1016/j.jcis.2008.02.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 02/19/2008] [Accepted: 02/25/2008] [Indexed: 11/17/2022]
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226
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Hofmann S, Sharma R, Wirth CT, Cervantes-Sodi F, Ducati C, Kasama T, Dunin-Borkowski RE, Drucker J, Bennett P, Robertson J. Ledge-flow-controlled catalyst interface dynamics during Si nanowire growth. NATURE MATERIALS 2008; 7:372-5. [PMID: 18327262 DOI: 10.1038/nmat2140] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 02/07/2008] [Indexed: 05/25/2023]
Abstract
Self-assembled nanowires offer the prospect of accurate and scalable device engineering at an atomistic scale for applications in electronics, photonics and biology. However, deterministic nanowire growth and the control of dopant profiles and heterostructures are limited by an incomplete understanding of the role of commonly used catalysts and specifically of their interface dynamics. Although catalytic chemical vapour deposition of nanowires below the eutectic temperature has been demonstrated in many semiconductor-catalyst systems, growth from solid catalysts is still disputed and the overall mechanism is largely unresolved. Here, we present a video-rate environmental transmission electron microscopy study of Si nanowire formation from Pd silicide crystals under disilane exposure. A Si crystal nucleus forms by phase separation, as observed for the liquid Au-Si system, which we use as a comparative benchmark. The dominant coherent Pd silicide/Si growth interface subsequently advances by lateral propagation of ledges, driven by catalytic dissociation of disilane and coupled Pd and Si diffusion. Our results establish an atomistic framework for nanowire assembly from solid catalysts, relevant also to their contact formation.
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Affiliation(s)
- Stephan Hofmann
- Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK.
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227
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Takagi D, Kobayashi Y, Hibino H, Suzuki S, Homma Y. Mechanism of gold-catalyzed carbon material growth. NANO LETTERS 2008; 8:832-5. [PMID: 18254601 DOI: 10.1021/nl0728930] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We demonstrate that nanosized Au particles have carbon solubility. Au-catalyzed carbon material growth by chemical vapor deposition undergoes a structural change, either a carbon nanowire or a single-walled carbon nanotube, depending on the catalyst particle size. This carbon material growth from Au is derived by the formation of Au-C eutectic nanosized alloy.
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Affiliation(s)
- Daisuke Takagi
- Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601, Japan
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228
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Allen JE, Hemesath ER, Perea DE, Lensch-Falk JL, Li ZY, Yin F, Gass MH, Wang P, Bleloch AL, Palmer RE, Lauhon LJ. High-resolution detection of Au catalyst atoms in Si nanowires. NATURE NANOTECHNOLOGY 2008; 3:168-73. [PMID: 18654490 DOI: 10.1038/nnano.2008.5] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 12/20/2007] [Indexed: 05/25/2023]
Abstract
The potential for the metal nanocatalyst to contaminate vapour-liquid-solid grown semiconductor nanowires has been a long-standing concern, because the most common catalyst material, Au, is highly detrimental to the performance of minority carrier electronic devices. We have detected single Au atoms in Si nanowires grown using Au nanocatalyst particles in a vapour-liquid-solid process. Using high-angle annular dark-field scanning transmission electron microscopy, Au atoms were observed in higher numbers than expected from a simple extrapolation of the bulk solubility to the low growth temperature. Direct measurements of the minority carrier diffusion length versus nanowire diameter, however, demonstrate that surface recombination controls minority carrier transport in as-grown n-type nanowires; the influence of Au is negligible. These results advance the quantitative correlation of atomic-scale structure with the properties of nanomaterials and can provide essential guidance to the development of nanowire-based device technologies.
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Affiliation(s)
- Jonathan E Allen
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
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229
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Ferralis N, Maboudian R, Carraro C. Temperature-induced self-pinning and nanolayering of AuSi eutectic droplets. J Am Chem Soc 2008; 130:2681-5. [PMID: 18251481 DOI: 10.1021/ja7101983] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A process for self-pinning of AuSi eutectic alloy droplets to a Si substrate, induced by a controlled temperature annealing in ultrahigh vacuum, is presented. Surface pinning of AuSi 3D droplets to the Si substrate is found to be a consequence of the readjustment in the chemical composition of the droplets upon annealing, as required to maintain thermodynamic equilibrium at the solid-liquid interface. Structural and morphological changes leading to the pinning of the droplets to the substrate are analyzed. Phase separation is observed upon cooling of the droplets, leading to the formation of amorphous Si-rich channels within the core and the formation of crystalline Si nanoshells on the outside. The mechanism leading to the pinning and surface layering provides new insight into the role of alloying during growth of silicon nanowires and may be relevant to the engineering of nanoscale Si cavities.
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Affiliation(s)
- Nicola Ferralis
- Department of Chemical Engineering, University of California, Berkeley, California 94720, USA
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230
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Sutter E, Sutter P. Phase diagram of nanoscale alloy particles used for vapor-liquid-solid growth of semiconductor nanowires. NANO LETTERS 2008; 8:411-4. [PMID: 18193910 DOI: 10.1021/nl0719630] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We use transmission electron microscopy observations to establish the parts of the phase diagram of nanometer sized Au-Ge alloy drops at the tips of Ge nanowires (NWs) that determine their temperature-dependent equilibrium composition and, hence, their exchange of semiconductor material with the NWs. We find that the phase diagram of the nanoscale drop deviates significantly from that of the bulk alloy, which explains discrepancies between actual growth results and predictions on the basis of the bulk-phase equilibria. Our findings provide the basis for tailoring vapor-liquid-solid growth to achieve complex one-dimensional materials geometries.
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Affiliation(s)
- Eli Sutter
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
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231
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Eustis S, Meier DC, Beversluis MR, Nikoobakht B. Analysis of copper incorporation into zinc oxide nanowires. ACS NANO 2008; 2:368-376. [PMID: 19206639 DOI: 10.1021/nn700332r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ZnO nanowires (NWs) are grown on a bulk copper half-transmission electron microscopy grid by chemical vapor deposition in a high temperature tube furnace. Photoluminescence (PL) microscopy revealed band gap emission at 380 nm and a more intense visible emission around 520 nm due to defect states in these NWs. High-resolution transmission electron microscopy shows that the ZnO NWs are single crystalline with hexagonal structure. Auger electron spectroscopy (AES) and energy dispersive X-ray spectroscopy reveal that copper atoms are present along the length of the NW. AES also found that the surface of the NWs is oxygen rich. The surface concentration of zinc increases moving from the tip toward the base of the NW while the concentration of oxygen decreases. The copper in this system not only remains at the tip of the growing NW but also acts as a dopant along the length of the NW, leading to a decrease in the intensity of the band gap PL of these NWs.
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Affiliation(s)
- Susie Eustis
- Surface and Microanalysis Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8372, Gaithersburg, Maryland 20899, USA
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232
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Adhikari H, Marshall AF, Goldthorpe IA, Chidsey CED, McIntyre PC. Metastability of Au-Ge liquid nanocatalysts: Ge vapor-liquid-solid nanowire growth far below the bulk eutectic temperature. ACS NANO 2007; 1:415-422. [PMID: 19206662 DOI: 10.1021/nn7001486] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The vapor-liquid-solid mechanism of nanowire (NW) growth requires the presence of a liquid at one end of the wire; however, Au-catalyzed Ge nanowire growth by chemical vapor deposition can occur at approximately 100 degrees C below the bulk Au-Ge eutectic. In this paper, we investigate deep sub-eutectic stability of liquid Au-Ge catalysts on Ge NWs quantitatively, both theoretically and experimentally. We construct a binary Au-Ge phase diagram that is valid at the nanoscale and show that equilibrium arguments, based on capillarity, are inconsistent with stabilization of Au-Ge liquid at deep sub-eutectic temperatures, similar to those used in Ge NW growth. Hot-stage electron microscopy and X-ray diffraction are used to test the predictions of nanoscale phase equilibria. In addition to Ge supersaturation of the Au-Ge liquid droplet, which has recently been invoked as an explanation for deep sub-eutectic Ge NW growth, we find evidence of a substantial kinetic barrier to Au solidification during cooling below the nanoscale Au-Ge eutectic temperature.
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Affiliation(s)
- Hemant Adhikari
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.
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233
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Eswaramoorthy SK, Howe JM, Muralidharan G. In Situ Determination of the Nanoscale Chemistry and Behavior of Solid-Liquid Systems. Science 2007; 318:1437-40. [DOI: 10.1126/science.1146511] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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234
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Chopra N, Gavalas VG, Bachas LG, Hinds BJ, Bachas LG. Functional One‐Dimensional Nanomaterials: Applications in Nanoscale Biosensors. ANAL LETT 2007. [DOI: 10.1080/00032710701567170] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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235
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Sadowski J, Dłuzewski P, Kret S, Janik E, Lusakowska E, Kanski J, Presz A, Terki F, Charar S, Tang D. GaAs:Mn nanowires grown by molecular beam epitaxy of (Ga,Mn)as at MnAs segregation conditions. NANO LETTERS 2007; 7:2724-8. [PMID: 17718585 DOI: 10.1021/nl071190f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
GaAs:Mn nanowires were obtained on GaAs(001) and GaAs(111)B substrates by molecular beam epitaxial growth of (Ga,Mn)As at conditions leading to MnAs phase separation. Their density is proportional to the density of catalyzing MnAs nanoislands, which can be controlled by the Mn flux and/or the substrate temperature. After deposition corresponding to a 200 nm thick (Ga,Mn)As layer the nanowires are around 700 nm long. Their shapes are tapered, with typical diameters around 30 nm at the base and 7 nm at the tip. The wires grow along the 111 direction, i.e., along the surface normal on GaAs(111)B and inclined on GaAs(001). In the latter case they tend to form branches. Being rooted in the ferromagnetic semiconductor (Ga,Mn)As, the nanowires combine one-dimensional properties with the magnetic properties of (Ga,Mn)As and provide natural, self-assembled structures for nanospintronics.
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Affiliation(s)
- Janusz Sadowski
- Groupe d'Etude des Semiconducteurs, Université de Montpellier 2, 34095 Montpellier, France.
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236
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Dayeh SA, Yu ET, Wang D. III-V nanowire growth mechanism: V/III ratio and temperature effects. NANO LETTERS 2007; 7:2486-90. [PMID: 17608541 DOI: 10.1021/nl0712668] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We have studied the dependence of Au-assisted InAs nanowire (NW) growth on InAs(111)B substrates as a function of substrate temperature and input V/III precursor ratio using organometallic vapor-phase epitaxy. Temperature-dependent growth was observed within certain temperature windows that are highly dependent on input V/III ratios. This dependence was found to be a direct consequence of the drop in NW nucleation and growth rate with increasing V/III ratio at a constant growth temperature due to depletion of indium at the NW growth sites. The growth rate was found to be determined by the local V/III ratio, which is dependent on the input precursor flow rates, growth temperature, and substrate decomposition. These studies advance understanding of the key processes involved in III-V NW growth, support the general validity of the vapor-liquid-solid growth mechanism for III-V NWs, and improve rational control over their growth morphology.
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Affiliation(s)
- Shadi A Dayeh
- Department of Electrical and Computer Engineering, University of California-San Diego, La Jolla, California 92093, USA
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237
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Mathur S, Shen H, Donia N, Rügamer T, Sivakov V, Werner U. One-Step Chemical Vapor Growth of Ge/SiCxNy Nanocables. J Am Chem Soc 2007; 129:9746-52. [PMID: 17629271 DOI: 10.1021/ja071931e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-step synthesis of one-dimensional Ge/SiCxNy core-shell nanocables was achieved by chemical vapor deposition of the molecular precursor [Ge{N(SiMe3)2}2]. Single crystalline Ge nanowires (diameter approximately 60 nm) embedded in uniform SiCxNy shells were obtained in high yields, whereby the growth process was not influenced by the nature of substrates. The shell material exhibited high oxidation and chemical resistance at elevated temperatures (up to 250 degrees C) resulting in the preservation of size-dependent semiconductor properties of germanium nanowires, such as intact transport of charge carriers and reduction of energy consumption, when compared to pure Ge nanowires.
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Affiliation(s)
- Sanjay Mathur
- Leibniz Institute of New Materials, Saarbruecken, Germany.
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238
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Affiliation(s)
- Volker Schmidt
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
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239
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Chen LJ. Silicon nanowires: the key building block for future electronic devices. ACTA ACUST UNITED AC 2007. [DOI: 10.1039/b709983e] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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