| 1. |
- Kawaguchi, Kenichi, et al.
(författare)
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InAs quantum dots and quantum wells grown on stacking-fault controlled InP nanowires with wurtzite crystal structure
- 2011
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:13
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Tidskriftsartikel (refereegranskat)abstract
- Heteroepitaxial growth of InAs was investigated on sidewalls of InP nanowires (NWs) using metal-organic vapor phase epitaxy. InAs quantum wells (QWs) with smooth surface were formed on the InP NWs having perfect wurtzite phase structure. On the other hand, InAs quantum dots (QDs) were formed on wurtzite InP NWs purposely introduced with stacking-fault segments. Photoluminescence from single NWs attributed to both QWs and QDs was observed. (C) 2011 American Institute of Physics. [doi:10.1063/1.3646386]
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| 2. |
- Berg, Alexander, et al.
(författare)
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In situ etching for control over axial and radial III-V nanowire growth rates using HBr.
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:50
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Tidskriftsartikel (refereegranskat)abstract
- We report on the influence of hydrogen bromide (HBr) in situ etching on the growth of InP, GaP and GaAs nanowires. We find that HBr can be used to impede undesired radial growth during axial growth for all three material systems. The use of HBr opens a window for optimizing the growth parameters with respect to the materials' quality rather than only their morphology. Transmission electron microscopy (TEM) characterization reveals a partial transition from a wurtzite crystal structure to a zincblende upon the use of HBr during growth. For InP, defect-related luminescence due to parasitic radial growth is removed by use of HBr. For GaP, the etching with HBr reduced the defect-related luminescence, but no change in peak emission energy was observed. For GaAs, the HBr etching resulted in a shift to lower photon emission energies due to a shift in the crystal structure, which reduced the wurtzite segments.
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| 3. |
- Bi, Zhaoxia, et al.
(författare)
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InN quantum dots on GaN nanowires grown by MOVPE
- 2014
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Ingår i: physica status solidi (c). - : Wiley. - 1862-6351 .- 1610-1642 .- 1610-1634. ; 11, s. 421-424
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Tidskriftsartikel (refereegranskat)abstract
- In this work, growth of InN quantum dots (QDs) on GaN nanowires (NWs) by metal-organic vapour phase epitaxy is demonstrated, illustrating the feasibility to combine 0D and 1D structures for nitride semiconductors. Selective area growth was used to generate arrays of c-oriented GaN NWs using Si3N4 as the mask material. In general, InN QDs tend to form at the NW edges between the m-plane side facets, but the QD growth can also be tuned to the side facets by controlling the growth temperature and the growth rate. TEM characterization reveals that I1-type stacking faults are formed in the QDs and originate from the misfit dislocations at the InN/GaN interface. Photoluminescence measurement at 4 K shows that the peak shifts to high energy with reduced dot size. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 4. |
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| 5. |
- Bi, Zhaoxia, et al.
(författare)
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Self-assembled InN quantum dots on side facets of GaN nanowires
- 2018
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:16
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembled, atomic diffusion controlled growth of InN quantum dots was realized on the side facets of dislocation-free and c-oriented GaN nanowires having a hexagonal cross-section. The nanowires were synthesized by selective area metal organic vapor phase epitaxy. A 3 Å thick InN wetting layer was observed after growth, on top of which the InN quantum dots formed, indicating self-assembly in the Stranski-Krastanow growth mode. We found that the InN quantum dots can be tuned to nucleate either preferentially at the edges between GaN nanowire side facets, or directly on the side facets by tuning the adatom migration by controlling the precursor supersaturation and growth temperature. Structural characterization by transmission electron microscopy and reciprocal space mapping show that the InN quantum dots are close to be fully relaxed (residual strain below 1%) and that the c-planes of the InN quantum dots are tilted with respect to the GaN core. The strain relaxes mainly by the formation of misfit dislocations, observed with a periodicity of 3.2 nm at the InN and GaN hetero-interface. The misfit dislocations introduce I1 type stacking faults (...ABABCBC...) in the InN quantum dots. Photoluminescence investigations of the InN quantum dots show that the emissions shift to higher energy with reduced quantum dot size, which we attribute to increased quantum confinement.
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| 6. |
- Borgström, Magnus, et al.
(författare)
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In Situ Etching for Total Control Over Axial and Radial Nanowire Growth
- 2010
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Ingår i: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 3:4, s. 264-270
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Tidskriftsartikel (refereegranskat)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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| 7. |
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| 8. |
- Ek, Martin, et al.
(författare)
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Compositional analysis of oxide-embedded III-V nanostructures
- 2022
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 33:37
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Tidskriftsartikel (refereegranskat)abstract
- Nanowire growth enables creation of embedded heterostructures, where one material is completely surrounded by another. Through materials-selective post-growth oxidation it is also possible to combine amorphous oxides and crystalline, e.g. III-V materials. Such oxide-embedded structures pose a challenge for compositional characterization through transmission electron microscopy since the materials will overlap in projection. Furthermore, materials electrically isolated by an embedding oxide are more sensitive to electron beam-induced alterations. Methods that can directly isolate the embedded material, preferably at reduced electron doses, will be required in this situation. Here, we analyse the performance of two such techniques-local lattice parameter measurements from high resolution micrographs and bulk plasmon energy measurements from electron energy loss spectra-by applying them to analyse InP-AlInP segments embedded in amorphous aluminium oxide. We demonstrate the complementarity of the two methods, which show an overall excellent agreement. However, in regions with residual strain, which we analyse through molecular dynamics simulations, the two techniques diverge from the true value in opposite directions.
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| 9. |
- Ek, Martin, et al.
(författare)
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Electron Image Series Reconstruction of Twin Interfaces in InP Superlattice Nanowires.
- 2011
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Ingår i: Microscopy and Microanalysis. - 1435-8115. ; 17:5, s. 752-758
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Tidskriftsartikel (refereegranskat)abstract
- The twin interface structure in twinning superlattice InP nanowires with zincblende structure has been investigated using electron exit wavefunction restoration from focal series images recorded on an aberration-corrected transmission electron microscope. By comparing the exit wavefunction phase with simulations from model structures, it was possible to determine the twin structure to be the ortho type with preserved In-P bonding order across the interface. The bending of the thin nanowires away from the intended ⟨110⟩ axis could be estimated locally from the calculated diffraction pattern, and this parameter was successfully taken into account in the simulations.
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| 10. |
- Lehmann, Sebastian, et al.
(författare)
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Simultaneous Growth of Pure Wurtzite and Zinc Blende Nanowires
- 2019
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 19:4, s. 2723-2730
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Tidskriftsartikel (refereegranskat)abstract
- The opportunity to engineer III-V nanowires in wurtzite and zinc blende crystal structure allows for exploring properties not conventionally available in the bulk form as well as opening the opportunity for use of additional degrees of freedom in device fabrication. However, the fundamental understanding of the nature of polytypism in III-V nanowire growth is still lacking key ingredients to be able to connect the results of modeling and experiments. Here we show InP nanowires of both pure wurtzite and pure zinc blende grown simultaneously on the same InP [100]-oriented substrate. We find wurtzite nanowires to grow along «111»B and zinc blende counterparts along «111»A. Further, we discuss the nucleation, growth, and polytypism of our nanowires against the background of existing theory. Our results demonstrate, first, that the crystal growth conditions for wurtzite and zinc blende nanowire growth are not mutually exclusive and, second, that the interface energies predominantly determine the crystal structure of the nanowires.
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