| 1. |
- Bernal, Ximena E., et al.
(författare)
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Empowering Latina scientists
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Paschoal Jr., Waldomiro, 1977-, et al.
(författare)
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Magnetoresistance in Mn ion-implanted GaAs:Zn nanowires
- 2014
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Ingår i: Applied Physics Letters. - New York : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 104:15
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the magnetoresistance (MR) in a series of Zn doped (p-type) GaAs nanowires implanted with different Mn concentrations. The nanowires with the lowest Mn concentration (~0.0001%) exhibit a low resistance of a few kΩ at 300K and a 4% positive MR at 1.6K, which can be well described by invoking a spin-split subband model. In contrast, nanowires with the highest Mn concentration (4%) display a large resistance of several MΩ at 300K and a large negative MR of 85% at 1.6K. The large negative MR is interpreted in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons, separated by intermediate regions of Mn impurity spins. Sweeping the magnetic field back and forth for the 4% sample reveals a hysteresis that indicates the presence of a weak ferromagnetic phase. We propose co-doping with Zn to be a promising way to reach the goal of realizing ferromagnetic Ga1-xMnxAs nanowires for future nanospintronics. © 2014 AIP Publishing LLC.
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| 3. |
- Johannes, A., et al.
(författare)
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Enhanced sputtering and incorporation of Mn in implanted GaAs and ZnO nanowires
- 2014
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Ingår i: Journal of Physics D: Applied Physics. - Bristol : IOP Publishing. - 1361-6463 .- 0022-3727. ; 47:39
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Tidskriftsartikel (refereegranskat)abstract
- We simulated and experimentally investigated the sputter yield of ZnO and GaAs nanowires, which were implanted with energetic Mn ions at room temperature. The resulting thinning of the nanowires and the dopant concentration with increasing Mn ion fluency were measured by accurate scanning electron microscopy (SEM) and nano-x-Ray Fluorescence (nanoXRF) quantification, respectively. We observed a clearly enhanced sputter yield for the irradiated nanowires compared to bulk, which is also corroborated by iradina simulations. These show a maximum if the ion range matches the nanowire diameter. As a consequence of the erosion thinning of the nanowire, the incorporation of the Mn dopants is also enhanced and increases non-linearly with increasing ion fluency.
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| 4. |
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| 5. |
- Dick Thelander, Kimberly, et al.
(författare)
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Growth of GaP nanotree structures by sequential seeding of 1D nanowires
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 272:1-4, s. 131-137
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Tidskriftsartikel (refereegranskat)abstract
- Complex nanostructures are becoming increasingly important for the development of nanoscale devices and functional nanomaterials. Precise control of size and morphology of these structures is critical to their fabrication and exploitation. We have developed a method for stepwise growth of tree-like nanostructures via the vapour liquid-solid (VLS) growth mode, demonstrated for III-V semiconductor materials. This method uses the initial seeding of nanowires by catalytic aerosol nanoparticles to form the trunk, followed by sequential seeding of branching structures. Here we present a detailed study of the growth of these complex structures using Gap. Diameter of each level of nanowires is directly determined by seed particle diameters, and number of branches is determined by seed particle density. Growth rate is shown to increase with temperature to a maximum corresponding to the temperature of complete decomposition of the Group-III precursor material, and subsequently decrease due to competition with bulk growth. Growth rate also depends on flow of the Group-III precursor, but not on the Group-V precursor. Finally, there is a relationship between the number of branches and their growth rate, suggesting that material diffusion plays a role in nanowire branch growth. (C) 2004 Elsevier B.V. All rights reserved.
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| 6. |
- Jurgilaitis, Andrius, et al.
(författare)
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Time-Resolved X-ray Diffraction Investigation of the Modified Phonon Dispersion in InSb Nanowires
- 2014
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Ingår i: Nano letters (Print). - Washington, DC : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 14:2, s. 541-546
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Tidskriftsartikel (refereegranskat)abstract
- The modified phonon dispersion is of importance for understanding the origin of the reduced heat conductivity in nanowires. We have measured the phonon dispersion for 50 nm diameter InSb (111) nanowires using time-resolved X-ray diffraction. By comparing the sound speed of the bulk (3880 m/s) and that of a classical thin rod (3600 m/s) to our measurement (2880 m/s), we conclude that the origin of the reduced sound speed and thereby to the reduced heat conductivity is that the C44 elastic constant is reduced by 35% compared to the bulk material. © 2014 American Chemical Society.
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| 7. |
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| 8. |
- Seifert, Werner, et al.
(författare)
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Growth of one-dimensional nanostructures in MOVPE
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 272:1-4, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- The use of metal organic vapor-phase epitaxy (MOVPE) for growth of one-dimensional nanostructures in the material systems GaAs, GaP, InAs and InP is investigated. Some kinetic effects are discussed, especially the general finding that in MOVPE thinner whiskers grow faster than thicker whiskers. Effects of growth temperature on growth rate and shape of the whiskers, the effects of different growth directions on the perfection of the materials and the possibilities to grow heterostructures in axial and lateral directions are reported. Ways to overcome the randomness in whisker growth by controlled seeding of the Au particles and by using lithography for site control are demonstrated.
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| 9. |
- Seifner, Michael S., et al.
(författare)
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Interface Dynamics in Ag–Cu3P Nanoparticle Heterostructures
- 2021
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126.
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Tidskriftsartikel (refereegranskat)abstract
- Earth-abundant transition metal phosphides are promising materials for energy-related applications. Specifically, copper(I) phosphide is such a material and shows excellent photocatalytic activity. Currently, there are substantial research efforts to synthesize well-defined metal–semiconductor nanoparticle heterostructures to enhance the photocatalytic performance by an efficient separation of charge carriers. The involved crystal facets and heterointerfaces have a major impact on the efficiency of a heterostructured photocatalyst, which points out the importance of synthesizing potential photocatalysts in a controlled manner and characterizing their structural and morphological properties in detail. In this study, we investigated the interface dynamics occurring around the synthesis of Ag–Cu3P nanoparticle heterostructures by a chemical reaction between Ag–Cu nanoparticle heterostructures and phosphine in an environmental transmission electron microscope. The major product of the Cu–Cu3P phase transformation using Ag–Cu nanoparticle heterostructures with a defined interface as a template preserved the initially present Ag{111} facet of the heterointerface. After the complete transformation, corner truncation of the faceted Cu3P phase led to a physical transformation of the nanoparticle heterostructure. In some cases, the structural rearrangement toward an energetically more favorable heterointerface has been observed and analyzed in detail at the atomic level. The herein-reported results will help better understand dynamic processes in Ag–Cu3P nanoparticle heterostructures and enable facet-engineered surface and heterointerface design to tailor their physical properties.
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| 10. |
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