| 1. |
- Aili, Daniel, 1977-, et al.
(author)
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Assembly of Polypeptide-Functionalized Gold Nanoparticles through a Heteroassociation- and Folding-Dependent Bridging
- 2008
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In: Nano letters (Print). - : ACS Publications. - 1530-6984 .- 1530-6992. ; 8:8, s. 2473-2478
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Journal article (peer-reviewed)abstract
- Gold nanoparticles were functionalized with a synthetic polypeptide, de novo-designed to associate with a charge complementary linker polypeptide in a folding-dependent manner. A heterotrimeric complex that folds into two disulphide-linked four-helix bundles is formed when the linker polypeptide associates with two of the immobilized peptides. The heterotrimer forms in between separate particles and induces a rapid and extensive aggregation with a well-defined interparticle spacing. The aggregated particles are redispersed when the disulphide bridge in the linker polypeptide is reduced.
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| 2. |
- Amini, Shahram, et al.
(author)
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On the Stability of Mg Nanograins to Coarsening after Repeated Melting
- 2009
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In: NANO LETTERS. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:8, s. 3082-3086
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Journal article (peer-reviewed)abstract
- Herein we report on the extraordinary thermal stability of similar to 35 nm Mg-nanograins that constitute the matrix of a Ti2AlC-Mg composite that has previously been shown to have excellent mechanical properties. The microstructure is so stable that heating the composite three times to 700 degrees C, which is 50 degrees C over the melting point of Mg, not only resulted in the repeated melting of the Mg, but surprisingly and within the resolution of our differential scanning calorimeter, did not lead to any coarsening. The reduction in the Mg melting point due to the nanograins was similar to 50 degrees C. X-ray diffraction and neutron spectroscopy results suggest that thin, amorphous, and/or poorly crystallized rutile, anatase, and/or magnesia layers separate the Mg nanograins and prevent them from coarsening. Clearly that layer is thin enough, and thus mechanically robust enough, to survive the melting and solidification stresses encountered during cycling. Annealing in hydrogen at 250 degrees C for 20 h, also did not seem to alter the grain size significantly.
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| 3. |
- Andersson, Viktor, et al.
(author)
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Imaging of the 3D Nanostructure of a Polymer Solar Cell by Electron Tomography
- 2009
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In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:2, s. 853-855
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Journal article (peer-reviewed)abstract
- Electron tomography has been used for analyzing the active layer in a polymer solar cell, a bulk heterojunction of an alternating copolymer of fluorene and a derivative of fullerene. The method supplies a three-dimensional representation of the morphology of the film, where domains with different scattering properties may be distinguished. The reconstruction shows good contrast between the two phases included in the film and demonstrates that electron tomography is an adequate tool for investigations of the three-dimensional nanostructure of the amorphous materials used in polymer solar cells.
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| 4. |
- Atalaya, Juan, 1981, et al.
(author)
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Continuum elastic modeling of graphene resonators
- 2008
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In: Nano Letters. - 1530-6992 .- 1530-6984. ; 8:12, s. 4196-4200
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Journal article (peer-reviewed)abstract
- Starting from an atomistic approach, we have derived a hierarchy of successively more simplified continuum elasticity descriptions for modeling the mechanical properties of suspended graphene sheets. We find that already for deflections of the order of 0.5 Å a theory that correctly accounts for nonlinearities is necessary and that for many purposes a set of coupled Duffing-type equations may be used to accurately describe the dynamics of graphene membranes. The descriptions are validated by applying them to square graphene-based resonators with clamped edges and studying numerically their mechanical responses. Both static and dynamic responses are treated, and we find good agreement with recent experimental findings.
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| 5. |
- Balocco, C, et al.
(author)
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Microwave detection at 110 GHz by nanowires with broken symmetry
- 2005
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:7, s. 1423-1427
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Journal article (peer-reviewed)abstract
- By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.
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| 6. |
- Bano, Fouzia, et al.
(author)
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Toward multiprotein nanoarrays using nanografting and DNA directed immobilization of proteins
- 2009
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:7, s. 2614-2618
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Journal article (peer-reviewed)abstract
- Atomic force microscopy nanografting was utilized to prepare DNA nanopatches of different sizes (200 × 200 to 1000 × 1000 nm2) onto which DNA−protein conjugates can be anchored through DNA-directed immobilization. Height measurements were used to assess the binding of the proteins as well as their subsequent interaction with other components, such as antibodies. The results indicate that nanografted patch arrays are well suited for application in biosensing and could enable the fabrication of multifeature protein nanoarrays.
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| 7. |
- Bao, Jiming, et al.
(author)
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Optical properties of rotationally twinned InP nanowire heterostructures
- 2008
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:3, s. 836-841
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Journal article (peer-reviewed)abstract
- We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in terms of the predicted staggered band alignment of the rotationally twinned zinc blende/wurzite InP heterostructure and of the concomitant diagonal transitions between localized electron and hole states responsible for radiative recombination. The ability of rotational twinning to introduce a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering.
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| 8. |
- Barauskas, Justas, et al.
(author)
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Self-assembled lipid superstructures: Beyond vesicles and liposomes
- 2005
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:8, s. 1615-1619
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Journal article (peer-reviewed)abstract
- A unique set of nanoparlicle dispersions of self-assembled lipid mesophases with distinctive reversed cubic, hexagonal, and sponge phase structures has been prepared by use of original lipid combinations and a simple, generally applicable and scalable method. All key properties, particle size distributions, shape, phase structure, and stability, are controlled predictably and reproducibly. The results suggest the cross-disciplinary use of nonlamellar particle structures in science and technology as, for instance, biomimetics, in vivo drug delivery vehicles for diagnostic and therapeutic agents, protein crystallization matrices, and soft nanoporous materials.
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| 9. |
- Berseth, P. A., et al.
(author)
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Carbon Nanomaterials as Catalysts for Hydrogen Uptake and Release in NaAlH4
- 2009
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In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:4, s. 1501-1505
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Journal article (peer-reviewed)abstract
- A synergistic approach involving experiment and first-principles theory not only shows that carbon nanostructures can be used as catalysts for hydrogen uptake and release in complex metal hydrides such as sodium alanate, NaAlH4, but also provides an unambiguous understanding of how the catalysts work. Here we show that the stability of NaAlH4 originates with the charge transfer from Na to the AlH4 moiety, resulting in an ionic bond between Na+ and AlH4- and a covalent bond between Al and H. Interaction of NaAlH4 with an electronegative substrate such as carbon fullerene or nanotube affects the ability of Na to donate its charge to AlH4, consequently weakening the Al-H bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H-2 to reverse the dehydrogenation reaction. In addition, based on our experimental observations and theoretical calculations it appears the curvature of the carbon nanostructure plays a role in the catalytic process. Ab initio molecular dynamics simulation further reveals the time evolution of the charge transfer process.
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| 10. |
- Björk, Per, et al.
(author)
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Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA
- 2005
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 5:10, s. 1948-1953
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Journal article (peer-reviewed)abstract
- DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.
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| 11. |
- Bogan, Michael J, et al.
(author)
-
Single particle X-ray diffractive imaging
- 2008
-
In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8:1, s. 310-6
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Journal article (peer-reviewed)abstract
- In nanotechnology, strategies for the creation and manipulation of nanoparticles in the gas phase are critically important for surface modification and substrate-free characterization. Recent coherent diffractive imaging with intense femtosecond X-ray pulses has verified the capability of single-shot imaging of nanoscale objects at suboptical resolutions beyond the radiation-induced damage threshold. By intercepting electrospray-generated particles with a single 15 femtosecond soft-X-ray pulse, we demonstrate diffractive imaging of a nanoscale specimen in free flight for the first time, an important step toward imaging uncrystallized biomolecules.
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| 12. |
- Börjesson, Anders, et al.
(author)
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Computational studies of metal-carbon nanotube interfaces for regrowth and electronic transport
- 2009
-
In: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 9:3, s. 1117-1120
-
Journal article (peer-reviewed)abstract
- First principles and tight binding Monte Carlo simulations show that junctions between single-walled carbon nanotubes (SWNTs) and nickel clusters are on the cluster surface, and not at subsurface sites, irrespective of the nanotube chirality, temperature, and whether the docking is gentle or forced. Gentle docking helps to preserve the pristine structure of the SWNT at the metal interface, whereas forced docking may partially dissolve the SWNT in the cluster. This is important for SWNT-based electronics and SWNT-seeded regrowth.
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| 13. |
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| 14. |
- Cheah, Seng Kian, et al.
(author)
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Self-Supported Three-Dimensional Nanoelectrodes for Microbattery Applications
- 2009
-
In: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 9:9, s. 3230-3233
-
Journal article (peer-reviewed)abstract
- A nanostructured three-dimensional (3D) microbattery has been produced and cycled in a Li-ion battery. It consists of a current collector of aluminum nanorods, a uniform layer of 17 nm TiO2 covering the nanorods made using ALD, an electrolyte and metallic lithium counter electrode. The battery is electrochemically cycled more than 50 times. The increase in total capacity is 10 times when using a 3D architechture compared to a 2D system for the same footprint area.
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| 15. |
- Ctistis, G., et al.
(author)
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Optical and Magnetic Properties of Hexagonal Arrays of Subwavelength Holes in Optically Thin Cobalt Films
- 2009
-
In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:1, s. 1-6
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Journal article (peer-reviewed)abstract
- In this study, we present our experimental results on the optical, magnetic, as well as magneto-optic properties of hexagonal arrays of subwavelength holes in optically thin cobalt films. Different meshes were used with hole diameters ranging between 220 and 330 nm while the interhole distance has been kept constant at 470 nm. The hole pattern modifies completely the magnetic behavior of the cobalt films; it gives rise to an increase of the coercive field of the in-plane magnetization with increasing hole diameter and to the appearance of out-of-plane magnetization components. Magneto-optic measurements show a spectacular magneto-optic response at wavelengths where surface plasmon-polaritons are supported by the structure as deduced in optical measurements. The experiments demonstrate the ability to artificially control the magnetic and thus the magneto-optic properties in hole array structures.
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| 16. |
- Czolkos, Ilja, 1980, et al.
(author)
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Controlled formation and mixing of two-dimensional fluids
- 2007
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:7, s. 1980-1984
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Journal article (peer-reviewed)abstract
- We introduce a novel technique for the controlled spreading and mixing of lipid monolayers from multilamellar precursors on surfaces covered by the hydrophobic epoxy resin SU-8. The lipid spreads as a monolayer as a result of the high surface tension between SU-8 and the aqueous environment. A micropatterned device with SU-8 lanes, injection pads, and mixing regions, surrounded by hydrophilic Au, was constructed to allow handling of lipid films and to achieve their mixing at controlled stoichiometry. Our findings offer a new approach to dynamic surface functionalization and decoration as well as surface-based catalysis and self-assembly.
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| 17. |
- Czolkos, Ilja, 1980, et al.
(author)
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Platform for Controlled Supramolecular Nano-Assembly
- 2009
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:6, s. 2482-2486
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Journal article (peer-reviewed)abstract
- We here present a two-dimensional (2D) micro/nano-fluidic technique where reactant-doped liquid−crystal films spread and mix on micro- and nanopatterned substrates. Surface-supported phospholipid monolayers are individually doped with complementary DNA molecules which hybridize when these lipid films mix. Using lipid films to convey reactants reduces the dimensionality of traditional 3D chemistry to 2D, and possibly to 1D by confining the lipid film to nanometer-sized lanes. The hybridization event was observed by FRET using single-molecule-sensitive confocal fluorescence detection. We could successfully detect hybridization in lipid streams on 250 nm wide lanes. Our results show that the number and density of reactants as well as sequence of reactant addition can be controlled within confined liquid crystal films, providing a platform for nanochemistry with potential for kinetic control.
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| 18. |
- Danilov, Andrey, 1961, et al.
(author)
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Electronic transport in single molecule junctions: Control of the molecule-electrode coupling through intramolecular tunneling barriers
- 2008
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:1, s. 1-5
-
Journal article (peer-reviewed)abstract
- We report on single molecule electron transport measurements of two oligophenylenevinylene (OPV3) derivatives placed in a nanogap between gold (Au) or lead (Pb) electrodes in a field effect transistor device. Both derivatives contain thiol end groups that allow chemical binding to the electrodes. One derivative has additional methylene groups separating the thiols from the delocalized pi-electron system. The insertion of methylene groups changes the open state conductance by 3-4 orders of magnitude and changes the transport mechanism from a coherent regime with finite zero-bias conductance to sequential tunneling and Coulomb blockade behavior.
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| 19. |
- Danilov, Andrey, 1961, et al.
(author)
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Nanoelectromechanical switch operating by tunneling of an entire C-60 molecule
- 2008
-
In: Nano Letters. - 1530-6992 .- 1530-6984. ; 8:8, s. 2393-2398
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Journal article (peer-reviewed)abstract
- We present a solid state single molecule electronic device where switching between two states with different conductance happens predominantly by tunneling of an entire C-60 molecule. This conclusion is based on a novel statistical analysis of similar to 10(5) switching events. The analysis yields (i) the relative contribution of tunneling, current induced heating and thermal fluctuations to the switching mechanism, (ii) the voltage dependent energy barrier (similar to 100-200 meV) separating the two states of the switch and (iii) the switching attempt frequency, omega(0) corresponding to a 2.8 meV mode, which is most likely rotational.
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| 20. |
- Diaz-Tendero, S., et al.
(author)
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Electron propagation along Cu nanowires supported on a Cu(111) surface
- 2008
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:9, s. 2712-2717
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Journal article (peer-reviewed)abstract
- We present a joint experimental-theoretical study of the one-dimensional band of excited electronic states with sp character localized on Cu nanowires supported on a Cu(III) surface. Energy dispersion and lifetime of these states have been obtained, allowing the determination of the mean distance traveled by an excited electron along the nanowire before it escapes into the substrate. We show that a Cu nanowire supported on a Cu(III) surface can guide a one-dimensional electron flux over a short distance and thus can be considered as a possible component for nanoelectronics devices.
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| 21. |
- Dick Thelander, Kimberly, et al.
(author)
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Control of GaP and GaAs Nanowire Morphology through Particle and Substrate Chemical Modification.
- 2008
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:11, s. 4087-4091
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Journal article (peer-reviewed)abstract
- We demonstrate two very different morphologies for GaP and GaAs nanowires grown by Au-assisted MOVPE on Si(111) substrates: rodlike wires and tapered wires with sharp tips. We show that the morphology is related to the stability of the particles at the wire tips during growth, and we propose that the mechanism of this effect is diffusion of Au away from the tip. Diffusion occurs, leading to tapered wires, only if there is a clean Si surface to act as a reservoir for the Au. Furthermore, the presence of indium in the particles, even at background levels from previous growth runs, inhibits the migration of Au. These results demonstrate a dramatic example of the sensitivity of wire morphology to substrate and particle chemistry, which could provide an important tool to tune nanowire morphology through particle alloying or surface treatment.
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| 22. |
- Dick Thelander, Kimberly, et al.
(author)
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Failure of the vapor-liquid-solid mechanism in Au-assisted MOVPE growth of InAs nanowires
- 2005
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:4, s. 761-764
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Journal article (peer-reviewed)abstract
- We report the temperature dependence of the Au-assisted growth of InAs nanowires in MOVPE. Extensive studies of the growth of such nanowires have attributed growth to the so-called vapor-liquid-solid (VLS) mechanism, with a liquid Au-In alloy particle. We assert here that growth is instead assisted by a solid particle and does not occur at all when the particle is a liquid. Thus the temperature range of InAs nanowire growth is limited by the melting of the Au-In alloy. Comparison with growth of InAs nanowires in the same system assisted by a layer of SiOx is used to support this conclusion.
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| 23. |
- Dick Thelander, Kimberly, et al.
(author)
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Position-controlled interconnected InAs nanowire networks
- 2006
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 6:12, s. 2842-2847
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Journal article (peer-reviewed)abstract
- We demonstrate here a method for controlled production of complex self-assembled three-dimensional networks of InAs nanowires on a substrate, based on sequentially seeded epitaxial nanowire structures, or "nanotrees". A position-controlled array of trunk nanowires is first produced using lithographically defined Au particles as seeds. With these wires positioned along the proper crystallographic directions with respect to each other, nanotree branches grow toward neighboring trunks, connecting them together. Finally, we investigate the crystal structure of the interconnected nanotrees, demonstrating that branch growth after the contact with the second trunk has an epitaxial relationship to that trunk.
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| 24. |
- Dick Thelander, Kimberly, et al.
(author)
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The morphology of axial and branched nanowire heterostructures
- 2007
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:6, s. 1817-1822
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Journal article (peer-reviewed)abstract
- We present an extensive investigation of the epitaxial growth of Au-assisted axial heterostructure nanowires composed of group IV and III-V materials and derive a model to explain the overall morphology of such wires. By analogy with 2D epitaxial growth, this model relates the wire morphology (i.e., whether it is kinked or straight) to the relationship of the interface energies between the two materials and the particle. This model suggests that, for any pair of materials, it should be easier to form a straight wire with one interface direction than the other, and we demonstrate this for the material combinations presented here. However, such factors as kinetics and the use of surfactants may permit the growth of straight double heterostructure nanowires. Finally, we demonstrate that branched nanowire heterostructures, also known as nanotrees, can be successfully explained by the same model.
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| 25. |
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