| 41. |
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| 42. |
- Bordag, Michael, et al.
(author)
-
Shear stress measurements on InAs nanowires by AFM manipulation
- 2007
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In: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
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Journal article (peer-reviewed)abstract
- On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
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| 43. |
- Borg, Mattias, et al.
(author)
-
GaAs/GaSb nanowire heterostructures grown by MOVPE
- 2008
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In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 310:18, s. 4115-4121
-
Journal article (peer-reviewed)abstract
- We report Au-assisted growth of GaAs/GaSb nanowire heterostructures on GaAs(1 1 1)B-substrates by metal-organic vapor phase epitaxy. The growth is studied at various precursor molar fractions and temperatures, in order to optimize the growth conditions for the GaSb nanowire segment. In contrast to most other III-V nanowire systems, the GaSb nanowire growth is Group V-limited under most conditions. We found that depending on the TMSb molar fraction, the seed particle is either supersaturated AuGa or AuGa2 during GaSb growth. The high Ga content in the particle gives a characteristic diameter increase between the GaAs and GaSb segment. From TEM and XEDS measurements we conclude that the GaSb nanowire growth occurs along either the AuGa-GaSb or AuGa2-GaSb pseudo-binaries of the Au-Ga-Sb ternary phase diagram. Finally, the GaSb nanowires exhibit untapered radial growth on the {1 (1) over bar 0} side facets. (C) 2008 Elsevier B.V. All rights reserved.
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| 44. |
- Borgström, Magnus, et al.
(author)
-
Dynamics of extremely anisotropic etching of InP nanowires by HCl
- 2011
-
In: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 502:4-6, s. 222-224
-
Journal article (peer-reviewed)abstract
- We report on the dynamics of in situ etching of nanowires using an etching agent which allows for parameter optimization for nanowire synthesis without concerns of tapering issues. Upon etching of InP nanowires using HCl it is found that HCl mainly reacts with the precursor TMI, its decomposition species, and physisorbed In. The reaction with solid InP is less rapid and diffusion limited. We find a gas-phase etch process which is metal assisted and has a high aspect ratio of 1:100. (C) 2011 Elsevier B.V. All rights reserved.
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| 45. |
- Borgström, Magnus, et al.
(author)
-
Fabrication and characterization of AlP-GaP core-shell nanowires
- 2011
-
In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 324:1, s. 290-295
-
Journal article (peer-reviewed)abstract
- We report on the particle assisted synthesis of core-shell AlP-GaP nanowires by use of metal-organic vapor phase epitaxy. The core-shell approach is chosen such as to stabilize the AlP which is highly sensitive to water. The nanowires were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. These nanowires have an indirect band-gap and form a type II staggered heterojunction. By designed capping of the AlP cores by GaP, we find the nanowires to be stable for more than a year. (C) 2011 Elsevier B.V. All rights reserved.
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| 46. |
- Borgström, Magnus, et al.
(author)
-
In Situ Etching for Total Control Over Axial and Radial Nanowire Growth
- 2010
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In: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 3:4, s. 264-270
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Journal article (peer-reviewed)abstract
- We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway, independent of other growth parameters. Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth. We demonstrate the method using etching by HCl during InP nanowire growth. The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.
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| 47. |
- Borgström, Magnus, et al.
(author)
-
Nanowires With Promise for Photovoltaics
- 2011
-
In: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 17:4, s. 1050-1061
-
Journal article (peer-reviewed)abstract
- Solar energy harvesting for electricity production is regarded as a fully credible future energy source: plentiful and without serious environmental concerns. The breakthrough for solar energy technology implementation has, however, been hampered by two issues: the conversion efficiency of light into electricity and the solar panel production cost. The use of III-V nanowires (NWs) in photovoltaics allows to respond to both these demands. They offer efficient light absorption and significant cost reduction. These low-dimensional structures can be grown epitaxially in dense NW arrays directly on silicon wafers, which are abundant and cheaper than the germanium substrates used for triple-junction solar cells today. For planar structures, lattice matching poses a strong restriction on growth. III-V NWs offer to create highly efficient multijunction devices, since multiple materials can be combined to match the solar spectrum without the need of tightly controlled lattice matching. At the same time, less material is required for NW-based solar cells than for planar-based architecture. This approach has potential to reach more than 50% in efficiency. Here, we describe our work on NW tandem solar cells, aiming toward two junctions absorbing different parts of the solar spectrum, connected in series via a tunnel diode.
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| 48. |
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| 49. |
- Borgström, Magnus, et al.
(author)
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Precursor evaluation for in situ InP nanowire doping
- 2008
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:44
-
Journal article (peer-reviewed)abstract
- The use of tetraethyltin (TESn) and dimethylzinc (DMZn) as in situ n- and p-dopant precursors during particle-assisted growth of InP nanowires is reported. Gate voltage dependent transport measurements demonstrate that the nanowires can be predictably synthesized as either n- or p-type. These doped nanowires can be characterized based on their electric field response and we find that n- type doping scales over a range from 10(17) to 10(19) cm(-3) with increasing input TESn dopant molar fraction. On the other hand, the p-type doping using DMZn saturates at low levels, probably related to a strong increase in nanowire growth rate with increasing DMZn molar fractions. By optimizing growth conditions with respect to tapering, axial pn-junctions exhibiting rectifying behavior were fabricated. The pn-junctions can be operated as light emitting diodes.
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| 50. |
- Borgström, Magnus, et al.
(author)
-
Site control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2003
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In: Journal of Crystal Growth. - 0022-0248. ; 248, s. 310-316
-
Journal article (peer-reviewed)abstract
- In this paper. we present the effect of annealing temperature and annealing time on InAs site-controlled quantum dot growth. Individual InAs quantum dots formed by self-assembling have been positioned into holes, created by partial overgrowth of electron beam induced nano-carbon deposits by metal organic vapor phase epitaxy. As/P exchange reactions produce material sufficient for selective dot nucleation in the holes. Results. showing that As/P exchange reactions occur even when capping the dots with InP are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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