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Electronic Structure Changes Due to Crystal Phase Switching at the Atomic Scale Limit

Knutsson, Johan Valentin LU ; Lehmann, Sebastian LU ; Hjort, Martin LU ; Lundgren, Edvin LU ; Dick, Kimberly A. LU ; Timm, Rainer LU and Mikkelsen, Anders LU (2017) In ACS Nano 11(10). p.10519-10528
Abstract

The perfect switching between crystal phases with different electronic structure in III-V nanowires allows for the design of superstructures with quantum wells only a single atomic layer wide. However, it has only been indirectly inferred how the electronic structure will vary down to the smallest possible crystal segments. We use low-temperature scanning tunneling microscopy and spectroscopy to directly probe the electronic structure of Zinc blende (Zb) segments in Wurtzite (Wz) InAs nanowires with atomic-scale precision. We find that the major features in the band structure change abruptly down to a single atomic layer level. Distinct Zb electronic structure signatures are observed on both the conduction and valence band sides for the... (More)

The perfect switching between crystal phases with different electronic structure in III-V nanowires allows for the design of superstructures with quantum wells only a single atomic layer wide. However, it has only been indirectly inferred how the electronic structure will vary down to the smallest possible crystal segments. We use low-temperature scanning tunneling microscopy and spectroscopy to directly probe the electronic structure of Zinc blende (Zb) segments in Wurtzite (Wz) InAs nanowires with atomic-scale precision. We find that the major features in the band structure change abruptly down to a single atomic layer level. Distinct Zb electronic structure signatures are observed on both the conduction and valence band sides for the smallest possible Zb segment: a single InAs bilayer. We find evidence of confined states in the region of both single and double bilayer Zb segments indicative of the formation of crystal segment quantum wells due to the smaller band gap of Zb as compared to Wz. In contrast to the internal electronic structure of the nanowire, surface states located in the band gap were found to be only weakly influenced by the presence of the smallest Zb segments. Our findings directly demonstrate the feasibility of crystal phase switching for the ultimate limit of atomistic band structure engineering of quantum confined structures. Further, it indicates that band gap values obtained for the bulk are reasonable to use even for the smallest crystal segments. However, we also find that the suppression of surface and interface states could be necessary in the use of this effect for engineering of future electronic devices.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
crystal phase, electronic structure, InAs, nanowire, STM/S, wurtzite, zinc blende
in
ACS Nano
volume
11
issue
10
pages
10 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85033470415
ISSN
1936-0851
DOI
10.1021/acsnano.7b05873
language
English
LU publication?
yes
id
0f1bff08-9d8e-41b5-ade2-4fe8e5e4af1f
date added to LUP
2017-11-21 07:48:42
date last changed
2017-11-22 03:00:02
@article{0f1bff08-9d8e-41b5-ade2-4fe8e5e4af1f,
  abstract     = {<p>The perfect switching between crystal phases with different electronic structure in III-V nanowires allows for the design of superstructures with quantum wells only a single atomic layer wide. However, it has only been indirectly inferred how the electronic structure will vary down to the smallest possible crystal segments. We use low-temperature scanning tunneling microscopy and spectroscopy to directly probe the electronic structure of Zinc blende (Zb) segments in Wurtzite (Wz) InAs nanowires with atomic-scale precision. We find that the major features in the band structure change abruptly down to a single atomic layer level. Distinct Zb electronic structure signatures are observed on both the conduction and valence band sides for the smallest possible Zb segment: a single InAs bilayer. We find evidence of confined states in the region of both single and double bilayer Zb segments indicative of the formation of crystal segment quantum wells due to the smaller band gap of Zb as compared to Wz. In contrast to the internal electronic structure of the nanowire, surface states located in the band gap were found to be only weakly influenced by the presence of the smallest Zb segments. Our findings directly demonstrate the feasibility of crystal phase switching for the ultimate limit of atomistic band structure engineering of quantum confined structures. Further, it indicates that band gap values obtained for the bulk are reasonable to use even for the smallest crystal segments. However, we also find that the suppression of surface and interface states could be necessary in the use of this effect for engineering of future electronic devices.</p>},
  author       = {Knutsson, Johan Valentin and Lehmann, Sebastian and Hjort, Martin and Lundgren, Edvin and Dick, Kimberly A. and Timm, Rainer and Mikkelsen, Anders},
  issn         = {1936-0851},
  keyword      = {crystal phase,electronic structure,InAs,nanowire,STM/S,wurtzite,zinc blende},
  language     = {eng},
  month        = {10},
  number       = {10},
  pages        = {10519--10528},
  publisher    = {The American Chemical Society},
  series       = {ACS Nano},
  title        = {Electronic Structure Changes Due to Crystal Phase Switching at the Atomic Scale Limit},
  url          = {http://dx.doi.org/10.1021/acsnano.7b05873},
  volume       = {11},
  year         = {2017},
}