liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Effects of Ni-coating on ZnO nanowires: A Raman scattering study
Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China .
Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea .
Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju 500712, Republic of Korea.
Show others and affiliations
2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 21, 214302-1-214302-6 p.Article in journal (Refereed) Published
Abstract [en]

Structural properties of ZnO/Ni core/shell nanowires (NWs) are studied in detail by means of Raman spectroscopy. It is shown that formation of the Ni shell leads to passivation of surface states responsible for the observed enhanced intensity of the A1(LO) Raman mode of the bare ZnO NWs. It also causes appearance of 490 cm−1 and 710 cm−1 modes that are attributed to local vibrational modes of a defect/impurity (or defects/impurities). This defect is concluded to be preferably formed in annealed ZnO/Ni NWs and is unlikely to contain a Ni atom, as the same Raman modes were also reported for the Ni-free ZnO nanostructures. From our resonant Raman studies, we also show that the ZnO/Ni core/shell NWs exhibit an enhanced Raman signal with a multiline structure involving A1(LO). This observation is attributed to combined effects of an enhanced Fröhlich interaction at the ZnO/Ni heterointerface and coupling of the scattered light with local surface plasmons excited in the Ni shell. The plasmonic effect is also suggested to allow detection of carbon-related species absorbed at the surface of a single ZnO/Ni NW, promising for applications of such structures as efficient nano-sized gas sensors.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013. Vol. 113, no 21, 214302-1-214302-6 p.
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:liu:diva-93878DOI: 10.1063/1.4807912OAI: oai:DiVA.org:liu-93878DiVA: diva2:627349
Available from: 2013-06-11 Created: 2013-06-11 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Optical properties of novel semiconductor nanostructures
Open this publication in new window or tab >>Optical properties of novel semiconductor nanostructures
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Semiconductor nanostructures, such as one-dimensional nanowires (NWs) and zerodimensional quantum dots (QDs), have recently gained increasing interest due to their unique physical properties that are found attractive for a wide variety of applications ranging from gas sensing and spintronics to optoelectronics and photonics. Here, especially promising are nanostructures based on compound semiconductors, including ZnO, GaNP and GaAs/InAs. For examples, ZnO NWs are used for gas sensing. They also serve as an active material in UV light sources, owing to its wide band gap combined with a large exciton binding energy. GaNP NWs are a novel material system that allows realization of efficient amber lightemitting diodes and novel intermediate-band solar cells with an anticipated high efficiency. InAs QDs formed in the GaAs matrix are efficient emitters of near IR light and can be utilized in future spin-functional devices for applications in spintronics and quantum information processing. The realization of the full potential of semiconductor nanostructures requires detailed knowledge of their electronic and structural properties which is far from being complete at the present stage of research. In this thesis we address some of these important issues using optical characterization techniques, such as micro-Raman and  microphotoluminescence (μ-PL) spectroscopies.

In paper I we use Raman spectroscopy to investigate effects of metallization by nickel on electronic and structural properties of ZnO/Ni core/shell NWs. We show that coating ZnO NWs with Ni shells causes passivation of surface states whereas subsequent annealing leads to formation of new defects, evident from appearance of the corresponding local vibrational modes. Ni coating is also found to strongly enhance the multiline Raman signal involving A1(LO) phonon scattering, based on the performed resonant Raman studies. This is attributed to an enhanced Fröhlich interaction at the ZnO/Ni heterointerface combined with coupling of the scattered light with local surface plasmons excited in the Ni shell. The latter effect is also suggested to allow detection of carbon-related species absorbed at the surface of a single ZnO/Ni NW, promising for utilizing such structures as efficient nano-sized gas sensors.

In paper II we study polarization properties of GaNP nanowires and related axial structures. By employing polarization resolved μ-PL spectroscopy performed on a single NW, we show that alloying with nitrogen allows one to achieve strong orthogonal polarization of light emission even in zinc-blende nanowires of various diameters and that the polarization anisotropy can be retained up to room temperature. This polarization response, which is unusual for zinc blende NWs, is attributed to the local strain in the vicinity of the N-related centers participating in the radiative recombination and to the preferential alignment of their principal axis along the growth direction. Our findings therefore show that defect engineering via alloying with nitrogen provides an additional degree of freedom to control the polarization anisotropy of III-V nanowires, advantageous for their applications as nanoscale emitters of polarized light.

In paper III we investigate exciton fine-structure splitting (FSS) in self-organized InGaAs/GaAs nanostructures including laterally-aligned double quantum dots (DQDs), quantum-dot clusters (QCs) and quantum rings (QRs), by employing polarization resolved μ-PL spectroscopy. We find a clear trend in FSS between the studied nanostructures depending on their geometric arrangements, from a large FSS in the DQDs to a smaller FSS in the QCs and QRs with an overall higher geometric symmetry. This trend is accompanied by a corresponding difference in the polarization directions of the excitonic emissions between these nanostructures, namely, the bright-exciton lines are linearly polarized along or perpendicular to a specific crystallographic axis in the DQDs structure that also defines the alignment of the two QDs, whereas in the QCs and QRs the polarization directions are randomly oriented. We attribute these trends to the interplay between intrinsic effects, such as a statistic shape deviation, atomistic randomness and strain-induced piezoelectricity. Our work demonstrates that FSS can be effectively controlled by geometric engineering of the nanostructures, capable of reducing FSS to the limit similar to strain-free QDs and thus providing a new pathway in fabricating high-symmetry quantum emitters desirable for realizing photon entanglement and spintronic devices based on such nanostructures.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. 34 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1691
National Category
Physical Sciences Nano Technology
Identifiers
urn:nbn:se:liu:diva-112355 (URN)978-91-7519-185-0 (ISBN)
Presentation
2014-12-17, Jordan-Fermi, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 09:30 (English)
Opponent
Supervisors
Note

The series name Linköping Studies in Science and Technology Licentiate Thesis is incorrect. The correct series name is Linköping Studies in Science and Technology Thesis.

Available from: 2014-11-24 Created: 2014-11-24 Last updated: 2017-03-27Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Filippov, StanislavChen, WeiminBuyanova, Irina

Search in DiVA

By author/editor
Filippov, StanislavChen, WeiminBuyanova, Irina
By organisation
Functional Electronic MaterialsThe Institute of Technology
In the same journal
Journal of Applied Physics
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 182 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf