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
Spatially direct and indirect transitions of self-assembled SiGe/Si quantum dots studied by photoluminescence excitation spectroscopy
Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-4547-6673
Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
Show others and affiliations
2010 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, no 18, 181107- p.Article in journal (Refereed) Published
Abstract [en]

Well-resolved photoluminescence excitation (PLE) spectra are reported for selfassembled SiGe dots grown on Si(100) by molecular beam epitaxy. The observation of two excitation resonance peaks is attributed to two different excitation/de-excitation routes of interband optical transitions connected to the spatially direct and indirect recombination processes. It is concluded that two dot populations are addressed by each monitored luminescence energy for the PLE acquisition.

Place, publisher, year, edition, pages
2010. Vol. 96, no 18, 181107- p.
Keyword [en]
Ge-Si alloys, luminescence, molecular beam epitaxial growth, self-assembly, semiconductor quantum dots
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-53204DOI: 10.1063/1.3424789ISI: 000277422000007OAI: oai:DiVA.org:liu-53204DiVA: diva2:287743
Note
Original Publication: Bouchaib Adnane, Fredrik Karlsson, Göran Hansson, Per-Olof Holtz and Wei-Xin Ni, Spatially direct and indirect transitions of self-assembled SiGe/Si quantum dots studied by photoluminescence excitation spectroscopy, 2010, Applied Physics Letters, (96), 18, 181107. http://dx.doi.org/10.1063/1.3424789 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2010-01-19 Created: 2010-01-19 Last updated: 2017-12-12
In thesis
1. Optical characterization of Silicon-based self-assembled nanostructures
Open this publication in new window or tab >>Optical characterization of Silicon-based self-assembled nanostructures
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This PhD thesis summarizes the work carried on the optical characterizations of some Si-based self-assembled nanostructures, particularly SiGe/Si quantum dots (QDs) and nanocrystalline (nc)-Si embedded in mesoporous silica (MS) using photoconductivity (PC), photoluminescence (PL), and photoluminescence excitation (PLE) measurements.

The spectroscopic studies of SiGe/Si QDs grown on Si by molecular beam epitaxy revealed for the first time well-resolved PLE resonances. When correlated with numerical analysis, these resonances were directly related to the co-existence of spatially direct (inside the SiGe dot) and indirect (across the Si/Ge interface) recombination processes involving different dot populations selected by the monitored detection energy for PLE acquisition. The characteristics of these two transitions were further studied in detail by PLE (in some case implemented together with selective PL) on various samples, which contained either only one Ge dot layer or multiple Gedot/Si stacks, grown at substrate temperatures ranging from 430 to 580 °C; especially the temperature- and excitation power-dependence of the excitation properties. The results illustrated that the electronic structure of SiGe dots are influenced by size, Ge composition, as well as strain connected, and sometimes a mixed effect.

Another attempt of the project was the fabrication of lateral transport mid-infrared photodetectors based on multiple Ge-dot/Si stacked structures. A broadband photoresponsivity of the processed multi-finger detectors was estimated to be about 90 mA/W over 3-15 μm range at 20 K, and the peaked photoresponse was measured at ~10 μm. The origin of the measured photocurrent, as elucidated by photoluminescence and photoluminescence excitation spectroscopies, was related to intersubband absorption of normal incidence infrared radiation corresponding to energies between the ground states of the heavy hole and the light hole in the valence band of the SiGe/Si QDs, and subsequent charge transfer to the Ge 2D wetting layer acting as a conduction channel. The absence of photocurrent in the energy range expected for a transition from the ground state to the first excited state of the heavy hole indicated that the holes in the SiGe dots behave essentially as 2D in character rather than a truly 3D confinement, where the transitions between heavy holes states are not allowed for TE polarized radiation (normal incidence).

Finally, Si(or Ge) nanocrystals embedded in mesoporous silica samples prepared by spincoating and atomic layer chemical vapor deposition were optically investigated by means of PL with various excitation powers, together with several attempts using different post rapid thermal annealing processes. The shape and energy position of the PL spectra of the nc-Si embedded in MS samples and a reference MS template without nc incorporation were rather similar, but the luminescence was much more intense for those embedded with nanocrystals. This implies that the emission mechanism for MS samples with or without nc-Si could be the same, i.e., the light emission was governed by the surface properties of silica. The semiconductor nanocrystals played a role by sensitizing the luminescence emission through generating more photo-excited carriers. These carriers were then trapped in the defect state e.g. the interfacial oxygen defect sites and subsequently recombine to increase the PL intensity.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 54 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1296
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-53206 (URN)978-91-7393-358-2 (ISBN)
Public defence
2010-06-17, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2010-01-19 Created: 2010-01-19 Last updated: 2011-02-04Bibliographically approved

Open Access in DiVA

fulltext(367 kB)471 downloads
File information
File name FULLTEXT01.pdfFile size 367 kBChecksum SHA-512
726c208dacf870696f6ef13ce55fa80612e9ced7fe71061e81ed3e9de6506fd7fd0427a9a9a8ae7204ff50fa90fb21ebb688f959873c3f76a29ba058d33836e5
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Adnane, BouchaibKarlsson, FredrikHansson, GöranHoltz, Per-OlofNi, Wei-Xin

Search in DiVA

By author/editor
Adnane, BouchaibKarlsson, FredrikHansson, GöranHoltz, Per-OlofNi, Wei-Xin
By organisation
Surface and Semiconductor Physics The Institute of TechnologySemiconductor Materials
In the same journal
Applied Physics Letters
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 471 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 341 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