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Conduction Band Offset and Polarization Effects in InAs Nanowire Polytype Junctions

Chen, I. Ju LU ; Lehmann, Sebastian LU ; Nilsson, Malin LU ; Kivisaari, Pyry LU ; Linke, Heiner LU ; Dick, Kimberly A. LU and Thelander, Claes LU (2017) In Nano Letters 17(2). p.902-908
Abstract

Although zinc-blende (ZB) and wurtzite (WZ) structures differ only in the atomic stacking sequence, mixing of crystal phases can strongly affect the electronic properties, a problem particularly common to bottom up-grown nanostructures. A lack of understanding of the nature of electronic transport at crystal phase junctions thus severely limits our ability to develop functional nanowire devices. In this work we investigated electron transport in InAs nanowires with designed mixing of crystal structures, ZB/WZ/ZB, by temperature-dependent electrical measurements. The WZ inclusion gives rise to an energy barrier in the conduction band. Interpreting the experimental result in terms of thermionic emission and using a drift-diffusion model,... (More)

Although zinc-blende (ZB) and wurtzite (WZ) structures differ only in the atomic stacking sequence, mixing of crystal phases can strongly affect the electronic properties, a problem particularly common to bottom up-grown nanostructures. A lack of understanding of the nature of electronic transport at crystal phase junctions thus severely limits our ability to develop functional nanowire devices. In this work we investigated electron transport in InAs nanowires with designed mixing of crystal structures, ZB/WZ/ZB, by temperature-dependent electrical measurements. The WZ inclusion gives rise to an energy barrier in the conduction band. Interpreting the experimental result in terms of thermionic emission and using a drift-diffusion model, we extracted values for the WZ/ZB band offset, 135 ± 10 meV, and interface sheet polarization charge density on the order of 10-3 C/m2. The extracted polarization charge density is 1-2 orders of magnitude smaller than previous experimental results, but in good agreement with first principle calculation of spontaneous polarization in WZ InAs. When the WZ length is reduced below 20 nm, an effective barrier lowering is observed, indicating the increasing importance of tunneling transport. Finally, we found that band-bending at ZB/WZ junctions can lead to bound electron states within an enclosed WZ segment of sufficient length, evidenced by our observation of Coulomb blockade at low temperature. These findings provide critical input for modeling and designing the electronic properties of novel functional devices, such as nanowire transistors, where crystal polytypes are commonly found.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
crystal structure, InAs, Nanowire, transport, wurtzite, zinc blende
in
Nano Letters
volume
17
issue
2
pages
7 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85011973249
  • wos:000393848800043
ISSN
1530-6984
DOI
10.1021/acs.nanolett.6b04211
language
English
LU publication?
yes
id
563fe1ae-9a89-408e-9e7c-4723f495fc2f
date added to LUP
2017-02-23 07:28:06
date last changed
2018-04-08 04:54:22
@article{563fe1ae-9a89-408e-9e7c-4723f495fc2f,
  abstract     = {<p>Although zinc-blende (ZB) and wurtzite (WZ) structures differ only in the atomic stacking sequence, mixing of crystal phases can strongly affect the electronic properties, a problem particularly common to bottom up-grown nanostructures. A lack of understanding of the nature of electronic transport at crystal phase junctions thus severely limits our ability to develop functional nanowire devices. In this work we investigated electron transport in InAs nanowires with designed mixing of crystal structures, ZB/WZ/ZB, by temperature-dependent electrical measurements. The WZ inclusion gives rise to an energy barrier in the conduction band. Interpreting the experimental result in terms of thermionic emission and using a drift-diffusion model, we extracted values for the WZ/ZB band offset, 135 ± 10 meV, and interface sheet polarization charge density on the order of 10<sup>-3</sup> C/m<sup>2</sup>. The extracted polarization charge density is 1-2 orders of magnitude smaller than previous experimental results, but in good agreement with first principle calculation of spontaneous polarization in WZ InAs. When the WZ length is reduced below 20 nm, an effective barrier lowering is observed, indicating the increasing importance of tunneling transport. Finally, we found that band-bending at ZB/WZ junctions can lead to bound electron states within an enclosed WZ segment of sufficient length, evidenced by our observation of Coulomb blockade at low temperature. These findings provide critical input for modeling and designing the electronic properties of novel functional devices, such as nanowire transistors, where crystal polytypes are commonly found.</p>},
  author       = {Chen, I. Ju and Lehmann, Sebastian and Nilsson, Malin and Kivisaari, Pyry and Linke, Heiner and Dick, Kimberly A. and Thelander, Claes},
  issn         = {1530-6984},
  keyword      = {crystal structure,InAs,Nanowire,transport,wurtzite,zinc blende},
  language     = {eng},
  month        = {02},
  number       = {2},
  pages        = {902--908},
  publisher    = {The American Chemical Society},
  series       = {Nano Letters},
  title        = {Conduction Band Offset and Polarization Effects in InAs Nanowire Polytype Junctions},
  url          = {http://dx.doi.org/10.1021/acs.nanolett.6b04211},
  volume       = {17},
  year         = {2017},
}