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Forrer N, Nigro A, Gadea G, Zardo I. Influence of Different Carrier Gases, Temperature, and Partial Pressure on Growth Dynamics of Ge and Si Nanowires. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2879. [PMID: 37947724 PMCID: PMC10650493 DOI: 10.3390/nano13212879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/23/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023]
Abstract
The broad and fascinating properties of nanowires and their synthesis have attracted great attention as building blocks for functional devices at the nanoscale. Silicon and germanium are highly interesting materials due to their compatibility with standard CMOS technology. Their combination provides optimal templates for quantum applications, for which nanowires need to be of high quality, with carefully designed dimensions, crystal phase, and orientation. In this work, we present a detailed study on the growth kinetics of silicon (length 0.1-1 μm, diameter 10-60 nm) and germanium (length 0.06-1 μm, diameter 10-500 nm) nanowires grown by chemical vapor deposition applying the vapour-liquid-solid growth method catalysed by gold. The effects of temperature, partial pressure of the precursor gas, and different carrier gases are analysed via scanning electron microscopy. Argon as carrier gas enhances the growth rate at higher temperatures (120 nm/min for Ar and 48 nm/min H2), while hydrogen enhances it at lower temperatures (35 nm/min for H2 and 22 nm/min for Ar) due to lower heat capacity. Both materials exhibit two growth regimes as a function of the temperature. The tapering rate is about ten times lower for silicon nanowires than for germanium ones. Finally, we identify the optimal conditions for nucleation in the nanowire growth process.
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Affiliation(s)
- Nicolas Forrer
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
| | - Arianna Nigro
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
| | - Gerard Gadea
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Ilaria Zardo
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; (N.F.); (A.N.); (G.G.)
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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2
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Lashani E, Amoozegar MA, Turner RJ, Moghimi H. Use of Microbial Consortia in Bioremediation of Metalloid Polluted Environments. Microorganisms 2023; 11:microorganisms11040891. [PMID: 37110315 PMCID: PMC10143001 DOI: 10.3390/microorganisms11040891] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/31/2023] Open
Abstract
Metalloids are released into the environment due to the erosion of the rocks or anthropogenic activities, causing problems for human health in different world regions. Meanwhile, microorganisms with different mechanisms to tolerate and detoxify metalloid contaminants have an essential role in reducing risks. In this review, we first define metalloids and bioremediation methods and examine the ecology and biodiversity of microorganisms in areas contaminated with these metalloids. Then we studied the genes and proteins involved in the tolerance, transport, uptake, and reduction of these metalloids. Most of these studies focused on a single metalloid and co-contamination of multiple pollutants were poorly discussed in the literature. Furthermore, microbial communication within consortia was rarely explored. Finally, we summarized the microbial relationships between microorganisms in consortia and biofilms to remove one or more contaminants. Therefore, this review article contains valuable information about microbial consortia and their mechanisms in the bioremediation of metalloids.
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Affiliation(s)
- Elham Lashani
- Extremophiles Laboratory, Department of Microbiology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14178-64411, Iran;
| | - Mohammad Ali Amoozegar
- Extremophiles Laboratory, Department of Microbiology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14178-64411, Iran;
- Correspondence: (M.A.A.); (H.M.); Tel.: +98-21-66415495 (H.M.)
| | - Raymond J. Turner
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada;
| | - Hamid Moghimi
- Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran 14178-64411, Iran
- Correspondence: (M.A.A.); (H.M.); Tel.: +98-21-66415495 (H.M.)
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3
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Sistani M, Böckle R, Falkensteiner D, Luong MA, den Hertog MI, Lugstein A, Weber WM. Nanometer-Scale Ge-Based Adaptable Transistors Providing Programmable Negative Differential Resistance Enabling Multivalued Logic. ACS NANO 2021; 15:18135-18141. [PMID: 34705418 DOI: 10.1021/acsnano.1c06801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The functional diversification and adaptability of the elementary switching units of computational circuits are disruptive approaches for advancing electronics beyond the static capabilities of conventional complementary metal-oxide-semiconductor-based architectures. Thereto, in this work the one-dimensional nature of monocrystalline and monolithic Al-Ge-based nanowire heterostructures is exploited to deliver charge carrier polarity control and furthermore to enable distinct programmable negative differential resistance at runtime. The fusion of electron and hole conduction together with negative differential resistance in a universal adaptive transistor may enable energy-efficient reconfigurable circuits with multivalued operability that are inherent components of emerging artificial intelligence electronics.
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Affiliation(s)
- Masiar Sistani
- Institute of Solid State Electronics, TU Wien, 1040 Vienna, Austria
| | - Raphael Böckle
- Institute of Solid State Electronics, TU Wien, 1040 Vienna, Austria
| | | | - Minh Anh Luong
- University Grenoble Alpes, CEA, IRIG-DEPHY-MEM-LEMMA, F-38000 Grenoble, France
| | | | - Alois Lugstein
- Institute of Solid State Electronics, TU Wien, 1040 Vienna, Austria
| | - Walter M Weber
- Institute of Solid State Electronics, TU Wien, 1040 Vienna, Austria
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Systematic investigation of structure and optoelectronic properties of Ge (n = 3–20), MGe9 (M = Ga, Si, Sn, As) and GaxGe(10−x) (x = 1–10) Clusters: Computational approach. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114874] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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5
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Lin CY, Chen CF, Chang YM, Yang SH, Lee KC, Wu WW, Jian WB, Lin YF. A Triode Device with a Gate Controllable Schottky Barrier: Germanium Nanowire Transistors and Their Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900865. [PMID: 31264786 DOI: 10.1002/smll.201900865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 06/12/2019] [Indexed: 06/09/2023]
Abstract
Electrical contacts often dominate charge transport properties at the nanoscale because of considerable differences in nanoelectronic device interfaces arising from unique geometric and electrostatic features. Transistors with a tunable Schottky barrier between the metal and semiconductor interface might simplify circuit design. Here, germanium nanowire (Ge NW) transistors with Cu3 Ge as source/drain contacts formed by both buffered oxide etching treatments and rapid thermal annealing are reported. The transistors based on this Cu3 Ge/Ge/Cu3 Ge heterostructure show ambipolar transistor behavior with a large on/off current ratio of more than 105 and 103 for the hole and electron regimes at room temperature, respectively. Investigations of temperature-dependent transport properties and low-frequency current fluctuations reveal that the tunable effective Schottky barriers of the Ge NW transistors accounted for the ambipolar behaviors. It is further shown that this ambipolarity can be used to realize binary-signal and data-storage functions, which greatly simplify circuit design compared with conventional technologies.
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Affiliation(s)
- Che-Yi Lin
- Department of Electrophysics, National Chiao Tung University, Hsinchu, 300, Taiwan
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chao-Fu Chen
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yuan-Ming Chang
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Shih-Hsien Yang
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Department of Electrical Engineering and Institute of Electronic Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Ko-Chun Lee
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Department of Electrical Engineering and Institute of Electronic Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Wen-Wei Wu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
- Center for the Intelligent Semiconductor Nano-system Technology Research, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Wen-Bin Jian
- Department of Electrophysics, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Yen-Fu Lin
- Department of Physics, National Chung Hsing University, Taichung, 40227, Taiwan
- Institute of Nanoscience, National Chung Hsing University, Taichung, 40227, Taiwan
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6
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Hanif I, Camara O, Tunes MA, Harrison RW, Greaves G, Donnelly SE, Hinks JA. Ion-beam-induced bending of semiconductor nanowires. NANOTECHNOLOGY 2018; 29:335701. [PMID: 29781443 DOI: 10.1002/admi.201800276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The miniaturisation of technology increasingly requires the development of both new structures as well as novel techniques for their manufacture and modification. Semiconductor nanowires (NWs) are a prime example of this and as such have been the subject of intense scientific research for applications ranging from microelectronics to nano-electromechanical devices. Ion irradiation has long been a key processing step for semiconductors and the natural extension of this technique to the modification of semiconductor NWs has led to the discovery of ion beam-induced deformation effects. In this work, transmission electron microscopy with in situ ion bombardment has been used to directly observe the evolution of individual silicon and germanium NWs under irradiation. Silicon NWs were irradiated with either 6 keV neon ions or xenon ions at 5, 7 or 9.5 keV with a flux of 3 × 1013 ions cm-2 s-1. Germanium NWs were irradiated with 30 or 70 keV xenon ions with a flux of 1013 ions cm-2 s-1. These new results are combined with those reported in the literature in a systematic analysis using a custom implementation of the transport of ions in matter Monte Carlo computer code to facilitate a direct comparison with experimental results taking into account the wide range of experimental conditions. Across the various studies this has revealed underlying trends and forms the basis of a critical review of the various mechanisms which have been proposed to explain the deformation of semiconductor NWs under ion irradiation.
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Affiliation(s)
- Imran Hanif
- School of Computing and Engineering, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, United Kingdom
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Katkar AS, Gupta SP, Seikh MM, Chen LJ, Walke PS. Room-temperature ferromagnetic Cr-doped Ge/GeO x core-shell nanowires. NANOTECHNOLOGY 2018; 29:235705. [PMID: 29553477 DOI: 10.1088/1361-6528/aab7a9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The Cr-doped tunable thickness core-shell Ge/GeOx nanowires (NWs) were synthesized and characterized using x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and magnetization studies. The shell thickness increases with the increase in synthesis temperature. The presence of metallic Cr and Cr3+ in core-shell structure was confirmed from XPS study. The magnetic property is highly sensitive to the core-shell thickness and intriguing room temperature ferromagnetism is realized only in core-shell NWs. The magnetization decreases with an increase in shell thickness and practically ceases to exist when there is no core. These NWs show remarkably high Curie temperature (TC > 300 K) with the dominating values of its magnetic remanence (MR) and coercivity (HC) compared to germanium dilute magnetic semiconductor nanomaterials. We believe that our finding on these Cr-doped Ge/GeOX core-shell NWs has the potential to be used as a hard magnet for future spintronic devices, owing to their higher characteristic values of ferromagnetic ordering.
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Affiliation(s)
- Amar S Katkar
- Dr. B N Purandare Arts and Smt. S G Gupta Commerce and Science College, Valvan, Lonavla, Pune-410403, India
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8
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Koleśnik-Gray M, Collins G, Holmes JD, Krstić V. Fingerprints of a size-dependent crossover in the dimensionality of electronic conduction in Au-seeded Ge nanowires. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:1574-1578. [PMID: 28144508 PMCID: PMC5238664 DOI: 10.3762/bjnano.7.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
We studied the electrical transport properties of Au-seeded germanium nanowires with radii ranging from 11 to 80 nm at ambient conditions. We found a non-trivial dependence of the electrical conductivity, mobility and carrier density on the radius size. In particular, two regimes were identified for large (lightly doped) and small (stronger doped) nanowires in which the charge-carrier drift is dominated by electron-phonon and ionized-impurity scattering, respectively. This goes in hand with the finding that the electrostatic properties for radii below ca. 37 nm have quasi one-dimensional character as reflected by the extracted screening lengths.
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Affiliation(s)
- Maria Koleśnik-Gray
- Department of Physics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Staudtstr. 7, 91058 Erlangen, Germany
| | - Gillian Collins
- Materials Chemistry & Analysis Group, Department of Chemistry, University College Cork, Cork, Republic of Ireland
| | - Justin D Holmes
- Materials Chemistry & Analysis Group, Department of Chemistry, University College Cork, Cork, Republic of Ireland
| | - Vojislav Krstić
- Department of Physics, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Staudtstr. 7, 91058 Erlangen, Germany
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9
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Yang PY, Ju SP, Lai ZM, Hsieh JY, Lin JS. The mechanical properties and thermal stability of ultrathin germanium nanowires. RSC Adv 2016. [DOI: 10.1039/c6ra21841e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The mechanical properties of ultrathin germanium nanowires are investigated: the mechanical properties of the nanowires are severely reduced when temperature increases.
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Affiliation(s)
- Po-Yu Yang
- Department of Mechanical and Electro-Mechanical Engineering
- National Sun Yat-sen University
- Kaohsiung 804
- Taiwan
| | - Shin-Pon Ju
- Department of Mechanical and Electro-Mechanical Engineering
- National Sun Yat-sen University
- Kaohsiung 804
- Taiwan
- Department of Medicinal and Applied Chemistry
| | - Zhu-Min Lai
- Department of Mechanical and Electro-Mechanical Engineering
- National Sun Yat-sen University
- Kaohsiung 804
- Taiwan
| | - Jin-Yuan Hsieh
- Department of Mechanical Engineering
- Minghsin University of Science and Technology
- Hsinchu 304
- Taiwan
| | - Jenn-Sen Lin
- Department of Mechanical Engineering
- National United University
- Taiwan
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10
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Mahenderkar NK, Liu YC, Koza JA, Switzer JA. Electrodeposited germanium nanowires. ACS NANO 2014; 8:9524-9530. [PMID: 25157832 DOI: 10.1021/nn503784d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Germanium (Ge) is a group IV semiconductor with superior electronic properties compared with silicon, such as larger carrier mobilities and smaller effective masses. It is also a candidate anode material for lithium-ion batteries. Here, a simple, one-step method is introduced to electrodeposit dense arrays of Ge nanowires onto indium tin oxide (ITO) substrates from aqueous solution. The electrochemical reduction of ITO produces In nanoparticles that act as a reduction site for aqueous Ge(IV) species, and as a solvent for the crystallization of Ge nanowires. Nanowires deposited at 95 °C have an average diameter of 100 nm, whereas those deposited at room temperature have an average diameter of 35 nm. Both optical absorption and Raman spectroscopy suggest that the electrodeposited Ge is degenerate. The material has an indirect bandgap of 0.90-0.92 eV, compared with a value of 0.67 eV for bulk, intrinsic Ge. The blue shift is attributed to the Moss-Burstein effect, because the material is a p-type degenerate semiconductor. On the basis of the magnitude of the blue shift, the hole concentration is estimated to be 8 × 10(19) cm(-3). This corresponds to an In impurity concentration of about 0.2 atom %. The resistivity of the wires is estimated to be 4 × 10(-5) Ω·cm. The high conductivity of the wires should make them ideal for lithium-ion battery applications.
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Affiliation(s)
- Naveen K Mahenderkar
- Department of Materials Science and Engineering and Graduate Center for Materials Research, Missouri University of Science and Technology , Rolla, Missouri 65409-1170, United States
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11
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Lahiri A, Willert A, Abedin SZE, Endres F. A simple and fast technique to grow free-standing germanium nanotubes and core-shell structures from room temperature ionic liquids. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.12.084] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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12
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Mohammad SN. Metal/nanowire contacts, quantum confinement, and their roles in the generation of new, gigantic actions in nanowire transistors. NANOTECHNOLOGY 2013; 24:455201. [PMID: 24129340 DOI: 10.1088/0957-4484/24/45/455201] [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
A distinctly new route for the design, modeling and electrical behavior of very short-channel (5-10 nm in channel length) nanowire field-effect transistors (FETs) has been presented. Essential elements of the approach entail a drain current determined by thermionic emission, but not by carrier mobility in the channel of the transistor. A basic understanding of the fundamental physics and the concepts of Schottky-barrier-based design for the proposed route have been described. Quantum confinement in the nanowire channel together with Schottky barrier tailing and temperature-dependent fluctuations of applied biases has been taken into account for the development of the model. Both current-voltage characteristics and transconductance of FETs have been studied. The calculated results are in near-quantitative agreement with the available experiments. Measured data show very diverse (e.g., exponential, linear, saturating, and non-linear non-exponential non-saturating) nanowire transistor characteristics. The model explains these characteristics well and reveals a number of new transistor actions. It highlights the impacts of quantum confinement and Schottky contacts for these new transistor actions. It also quantifies the significant enhancement of the drain-source current and transconductance. With new findings thus achieved, suggestions for the realization of very high-performance, small-diameter (preferably 2 nm), small-Schottky-barrier-height, high-operating temperature, ultra-short-channel-length, nanowire transistors have been made. Optimized design of these transistors has been suggested. And the range (in terms of device and technological parameters) of the proposed model has been elucidated.
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Reparaz JS, Peica N, Kirste R, Goñi AR, Wagner MR, Callsen G, Alonso MI, Garriga M, Marcus IC, Ronda A, Berbezier I, Maultzsch J, Thomsen C, Hoffmann A. Probing local strain and composition in Ge nanowires by means of tip-enhanced Raman scattering. NANOTECHNOLOGY 2013; 24:185704. [PMID: 23579463 DOI: 10.1088/0957-4484/24/18/185704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Local strain and Ge content distribution in self-assembled, in-plane Ge/Si nanowires grown by combining molecular beam epitaxy and the metal-catalyst assisted-growth method were investigated by tip-enhanced Raman scattering. We show that this technique is essential to study variations of physical properties of single wires at the nanoscale, a task which cannot be achieved with conventional micro-Raman scattering. As two major findings, we report that (i) the Ge distribution in the (001) crystallographic direction is inhomogeneous, displaying a gradient with a higher Ge content close to the top surface, and (ii) in contrast, the (uncapped) wires exhibit essentially the same small residual compressive strain everywhere along the wire.
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Affiliation(s)
- J S Reparaz
- Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany.
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Ma JW, Lee WJ, Bae JM, Jeong KS, Kang YS, Cho MH, Seo JH, Ahn JP, Chung KB, Song JY. Effects of surface chemical structure on the mechanical properties of Si(1-x)Ge(x) nanowires. NANO LETTERS 2013; 13:1118-1125. [PMID: 23421739 DOI: 10.1021/nl304485d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Young's modulus and fracture strength of Si(1-x)Ge(x) nanowires (NWs) as a function of Ge concentration were measured from tensile stress measurements. The Young's modulus of the NWs decreased linearly with increasing Ge content. No evidence was found for a linear relationship between the fracture strength of the NWs and Ge content, which is closely related to the quantity of interstitial Ge atoms contained in the wire. However, by removing some of the interstitial Ge atoms through rapid thermal annealing, a linear relationship could be produced. The discrepancy in the reported strength of Si and Ge NWs between calculated and experimented results could be related to SiO(2-x)/Si interfacial defects that are found in Si(1-x)Ge(x) NWs. It was also possible to significantly decrease the number of interfacial defects in the NWs by incorporating a surface passivated Al2O3 layer, which resulted in a substantial increase in fracture strength.
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Affiliation(s)
- J W Ma
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Korea
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15
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Sk MA, Ng MF, Huang L, Lim KH. Modulating the electronic properties of germanium nanowires via applied strain and surface passivation. Phys Chem Chem Phys 2013; 15:5927-35. [DOI: 10.1039/c3cp43530j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Sk MA, Ng MF, Yang SW, Lim KH. Stress induced half-metallicity in surface defected germanium nanowires. Phys Chem Chem Phys 2012; 14:1166-74. [DOI: 10.1039/c1cp22262g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Tsai CY, Yu SY, Hsin CL, Huang CW, Wang CW, Wu WW. Growth and properties of single-crystalline Ge nanowires and germanide/Ge nano-heterostructures. CrystEngComm 2012. [DOI: 10.1039/c1ce06107k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Li X, Meng G, Xu Q, Kong M, Zhu X, Chu Z, Li AP. Controlled synthesis of germanium nanowires and nanotubes with variable morphologies and sizes. NANO LETTERS 2011; 11:1704-1709. [PMID: 21417314 DOI: 10.1021/nl200229p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report on the controlled growth of germanium (Ge) nanostructures in the form of both nanowire (NW) and nanotube (NT) with ultrahigh aspect ratios and variable diameters. The nanostructures are grown inside a porous anodic aluminum oxide (AAO) template by low-temperature chemical vapor deposition (CVD) assisted by an electrodeposited metal nanorod catalyst. Depending on the choice of catalytic metals (Au, Ni, Cu, Co) and germane (GeH(4)) concentration during CVD, either Ge NWs or NTs can be synthesized at low growth temperatures (310-370 °C). Furthermore, Ge NWs and NTs with two or more branches can be grown from the same stem while using AAO with branched channels as templates. Transmission electron microscopy studies show that NWs are single crystalline and that branches grow epitaxially from the stem of NWs with a crystalline direction independent of diameter. As-grown NTs are amorphous but can crystallize via postannealing at 400 °C in Ar/H(2) atmosphere, with a wall thickness controllable between 6 and 18 nm in the CVD process. The yield and quality of the NTs are critically dependent on the choice of the catalyst, where Ni appears the best choice for Ge NT growth among Ni, Cu, Co, and Au. The synthesis of structurally uniform and morphologically versatile Ge nanostructures may open up new opportunities for integrated Ge-nanostructure-based nanocircuits, nanodevices, and nanosystems.
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Affiliation(s)
- Xiangdong Li
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
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19
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Sk MA, Ng MF, Yang SW, Lim KH. Water induced electrical hysteresis in germanium nanowires: a theoretical study. Phys Chem Chem Phys 2011; 13:11663-70. [DOI: 10.1039/c1cp20228f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chien CY, Chang YJ, Chang JE, Lee MS, Chen WY, Hsu TM, Li PW. Formation of Ge quantum dots array in layer-cake technique for advanced photovoltaics. NANOTECHNOLOGY 2010; 21:505201. [PMID: 21098937 DOI: 10.1088/0957-4484/21/50/505201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report a simple and manageable growth method for placing dense three-dimensional Ge quantum dot (QD) arrays in a uniform or a graded size distribution, based on thermally oxidizing stacked poly-SiGe in a layer-cake technique. The QD size and spatial density in each stack can be modulated by conditions of the Ge content in poly-Si(1-x)Ge(x), oxidation, and the underlay buffer layer. Size-dependent internal structure, strain, and photoluminescence properties of Ge QDs are systematically investigated. Optimization of the processing conditions could be carried out for producing dense Ge QD arrays to maximize photovoltaic efficiency.
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Affiliation(s)
- C Y Chien
- Department of Electrical Engineering, National Central University, ChungLi, 320, Taiwan, Republic of China
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Wang M, Chen S, Xia Y, Zhang Y, Huang W, Zheng J, Li Z. Nanoassemblies of colloidal gold nanoparticles by oxygen-induced inorganic ligand replacement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9351-9356. [PMID: 20232809 DOI: 10.1021/la100329a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This article reports a novel method of the fabrication of floating ultrathin nanoporous films and superlattice-like bottom sediment flakes of colloidal gold nanoparticles (Au NPs) by the oxygen-induced ligand replacement of inorganic species. The two nanoassemblies were realized in a weighing bottle simply by aging the Au colloid, which was synthesized and stabilized using more divalent tin Sn(II) than required for the reduction of HAuCl(4). In situ Raman spectroscopy was employed to trace the assembly process, and we found that the protective Sn(II) species (mostly SnCl(3)(-)) of the gold colloid could be gradually replaced by Cl(-) ions in the solution, while the strongly chemically adsorbed Sn(II) species on the Au NPs was oxidized by O(2) from the air contact. The destabilized colloidal Au NPs by the ligand replacement of SnCl(3)(-) with Cl(-) first assembled into an ultrathin nanoporous film at the air-water interface and then sedimentated to the bottom. Superlattice-like sediment flakes of Au NPs can be obtained at lower temperature (approximately 5 degrees C). Particularly, this method does not involve any organic substances, providing clean ultrathin nanoporous films and superlattice-like flakes of Au NPs. The ultrathin nanoporous films and superlattice-like flakes of Au NPs can serve as SERS substrates with strong and long activity.
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Affiliation(s)
- Minghua Wang
- Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 China
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Sierra-Sastre Y, Dayeh SA, Picraux ST, Batt CA. Epitaxy of Ge nanowires grown from biotemplated Au nanoparticle catalysts. ACS NANO 2010; 4:1209-1217. [PMID: 20128609 DOI: 10.1021/nn901664r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Semiconductor nanowires (NWs) are being actively investigated due to their unique functional properties which result from their quasi-one-dimensional structure. However, control over the crystallographic growth direction, diameter, location, and morphology of high-density NWs is essential to achieve the desirable properties and to integrate these NWs into miniaturized devices. This article presents evidence for the suitability of a biological templated catalyst approach to achieve high-density, epitaxial growth of NWs via the vapor-liquid-solid (VLS) mechanism. Bacterial surface-layer protein lattices from Deinococcus radiodurans were adsorbed onto germanium substrates of (111), (110), and (100) crystallographic orientations and used to template gold nanoparticles (AuNPs) of different diameters. Orientation-controlled growth of GeNWs was achieved from very small size (5-20 nm) biotemplated AuNP catalysts on all of the substrates studied. Biotemplated GeNWs exhibited improved morphologies, higher densities (NW/microm(2)), and more uniform length as compared to GeNWs grown from nontemplated AuNPs on the substrate surfaces. The results offer an integrated overview of the interplay of parameters such as catalyst size, catalyst density, substrate crystallographic orientation, and the presence of the protein template in determining the morphology and growth direction of GeNWs. A comparison between templated and nontemplated growth provides additional insight into the mechanism of VLS growth of biotemplated NWs.
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Affiliation(s)
- Yajaira Sierra-Sastre
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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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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Mouchet C, Latu-Romain L, Cayron C, Rouviere E, Celle C, Simonato JP. Growth of one-dimensional Si/SiGe heterostructures by thermal CVD. NANOTECHNOLOGY 2008; 19:335603. [PMID: 21730625 DOI: 10.1088/0957-4484/19/33/335603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The first results on a simple new process for the direct fabrication of one-dimensional superlattices using common CVD chambers are presented. The experiments were carried out in a 200 mm industrial Centura reactor (Applied Materials). Low dimensionality and superlattices allow a significant increase in the figure of merit of thermoelectrics by controlling the transport of phonons and electrons. The monocrystalline nanowires produced according to this process are both one-dimensional and present heterostructures, with very thin layers (40 nm) of Si and SiGe. Concentrations up to 30 at.% Ge were obtained in the SiGe parts. Complementary techniques including transmission electronic microscopy (TEM), selected area electron diffraction (SAED), energy dispersive x-ray spectroscopy (EDS), scanning transmission electron microscopy (STEM) in bright field and high angle annular dark field (HAADF STEM), and energy-filtered transmission electron microscopy (EF-TEM) were used to characterize the nanoheterostructures.
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