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Phase Transformation in Radially Merged Wurtzite GaAs Nanowires.

Jacobsson, Daniel LU ; Yang, Fangfang LU ; Hillerich, Karla LU ; Lenrick, Filip LU ; Lehmann, Sebastian LU ; Kriegner, Dominik; Stangl, Julian; Wallenberg, Reine LU ; Dick Thelander, Kimberly LU and Johansson, Jonas LU (2015) In Crystal Growth & Design 15(10). p.4795-4803
Abstract
III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In particular, we investigated what happens when adjacent WZ NWs radially merge with each other by analyzing the evolution of XRD peaks for different amounts of radial overgrowth and merging. By preparing cross-sectional lamella samples we also analyzed the local crystal structure of partly merged NWs by transmission electron microscopy. Once... (More)
III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In particular, we investigated what happens when adjacent WZ NWs radially merge with each other by analyzing the evolution of XRD peaks for different amounts of radial overgrowth and merging. By preparing cross-sectional lamella samples we also analyzed the local crystal structure of partly merged NWs by transmission electron microscopy. Once individual NWs start to merge, the crystal structure of the merged segments is transformed progressively from initial pure WZ to a mixed WZ/ZB structure. The merging process is then modeled using a simple combinatorial approach, which predicts that merging of two or more WZ NWs will result in a mixed crystal structure containing WZ, ZB, and 4H. The existence large and relaxed segments of 4H structure within the merged NWs was confirmed by XRD, allowing us to accurately determine the lattice parameters of GaAs 4H. We compare the measured WZ and 4H unit cells with an ideal tetrahedron and find that both the polytypes are elongated in the c-axis and compressed in the a-axis compared to the geometrically converted cubic ZB unit cell. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Crystal Growth & Design
volume
15
issue
10
pages
4795 - 4803
publisher
The American Chemical Society
external identifiers
  • pmid:26494983
  • wos:000362628800011
  • scopus:84943563482
ISSN
1528-7483
DOI
10.1021/acs.cgd.5b00507
language
English
LU publication?
yes
id
8de76c87-0e45-4e37-b2a1-881477dcb23a (old id 8148552)
date added to LUP
2015-11-18 16:59:25
date last changed
2017-09-17 04:02:12
@article{8de76c87-0e45-4e37-b2a1-881477dcb23a,
  abstract     = {III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In particular, we investigated what happens when adjacent WZ NWs radially merge with each other by analyzing the evolution of XRD peaks for different amounts of radial overgrowth and merging. By preparing cross-sectional lamella samples we also analyzed the local crystal structure of partly merged NWs by transmission electron microscopy. Once individual NWs start to merge, the crystal structure of the merged segments is transformed progressively from initial pure WZ to a mixed WZ/ZB structure. The merging process is then modeled using a simple combinatorial approach, which predicts that merging of two or more WZ NWs will result in a mixed crystal structure containing WZ, ZB, and 4H. The existence large and relaxed segments of 4H structure within the merged NWs was confirmed by XRD, allowing us to accurately determine the lattice parameters of GaAs 4H. We compare the measured WZ and 4H unit cells with an ideal tetrahedron and find that both the polytypes are elongated in the c-axis and compressed in the a-axis compared to the geometrically converted cubic ZB unit cell.},
  author       = {Jacobsson, Daniel and Yang, Fangfang and Hillerich, Karla and Lenrick, Filip and Lehmann, Sebastian and Kriegner, Dominik and Stangl, Julian and Wallenberg, Reine and Dick Thelander, Kimberly and Johansson, Jonas},
  issn         = {1528-7483},
  language     = {eng},
  number       = {10},
  pages        = {4795--4803},
  publisher    = {The American Chemical Society},
  series       = {Crystal Growth & Design},
  title        = {Phase Transformation in Radially Merged Wurtzite GaAs Nanowires.},
  url          = {http://dx.doi.org/10.1021/acs.cgd.5b00507},
  volume       = {15},
  year         = {2015},
}