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Weman, Helge
Publications (10 of 20) Show all publications
Weman, H., Palmgren, S., Karlsson, F., Rudra, A., Kapon, E., Dheeraj, D., . . . Harmand, J. (2009). Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications. Journal of materials science. Materials in electronics, 20(1), S94-S101
Open this publication in new window or tab >>Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications
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2009 (English)In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 20, no 1, p. S94-S101Article in journal (Refereed) Published
Abstract [en]

Exciton transfer between two parallel GaAs V-groove quantum wires (QWRs) or two planar quantum wells (QWs) separated by AlGaAs barriers ranging from 5.5 nm to 20 nm thickness is studied by photoluminescence (PL) and PL excitation (PLE) spectroscopy. It is found that the transfer is strongly reduced between the widely spaced QWRs as compared with QWs. We have also investigated the optical absorption in single QWRs embedded in an AlGaAs V-shaped channel waveguide. Using a combination of PLE and absorption measurements we construct the full dependence of absorption spectra on the linear polarization. Our studies reveal the importance of inter-subband mixing in determining the energies of the light-hole-like transitions and thus the QWR absorption. Finally we present recent results on the fabrication and structural characterization of GaAs and GaP nanowires (NWs) grown by molecular beam epitaxy (MBE) on GaAs(111)B and Si(111) substrates, using Au-catalyzed vapor–liquid–solid growth technique. It is shown that, apart from optimizing the NW growth parameters, substrate material and the procedure for preparing the substrate before the MBE growth play an important role in controlling the NWs.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44838 (URN)10.1007/s10854-007-9456-5 (DOI)77813 (Local ID)77813 (Archive number)77813 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Moses, A., Hoang, T., Dheeraj, D., Fimland, B., Weman, H., Karlsson, F. & Holtz, P.-O. (2008). Investigation of the structural and optical properties of single GaAs/GaAsSb/GaAs nanowire quantum dots. In: 17th International Laser Physics Workshop,2008.
Open this publication in new window or tab >>Investigation of the structural and optical properties of single GaAs/GaAsSb/GaAs nanowire quantum dots
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2008 (English)In: 17th International Laser Physics Workshop,2008, 2008Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44104 (URN)75547 (Local ID)75547 (Archive number)75547 (OAI)
Note
TalkAvailable from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
Moses, A., Dheeraj, D., Fimland, B., Weman, H., Karlsson, F. & Holtz, P.-O. (2008). Micro-photoluminescence study of heterostructured GaAs/AlGaAs and GaAs/GaAsSb nanowires grown by molecular beam epitaxy. In: 29th International Conference on the Physics of Semiconductors ICPS,2008.
Open this publication in new window or tab >>Micro-photoluminescence study of heterostructured GaAs/AlGaAs and GaAs/GaAsSb nanowires grown by molecular beam epitaxy
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2008 (English)In: 29th International Conference on the Physics of Semiconductors ICPS,2008, 2008Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44068 (URN)75504 (Local ID)75504 (Archive number)75504 (OAI)
Note
PosterAvailable from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
Weman, H., Palmgren, S., Karlsson, F., Kapon, E., Dasa, D. & Fimland, B.-O. (2007). Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications. In: The International Conference on Optical, Optoelectronic and Photonic Materials and Applications ICOOPMA,2007.
Open this publication in new window or tab >>Semiconductor Quantum-Wires and Nano-Wires for optoelectronic Applications
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2007 (English)In: The International Conference on Optical, Optoelectronic and Photonic Materials and Applications ICOOPMA,2007, 2007Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44839 (URN)77815 (Local ID)77815 (Archive number)77815 (OAI)
Note

INVITED TALK

Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
Karlsson, F., Weman, H., Leifer, K., Rudra, A., Kapon, E. & Lyo, S. (2007). Strongly reduced exciton transfer between parallel quantum wires. Applied Physics Letters, 90, 101108
Open this publication in new window or tab >>Strongly reduced exciton transfer between parallel quantum wires
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2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, p. 101108-Article in journal (Refereed) Published
Abstract [en]

Exciton transfer between two parallel GaAs V-groove quantum wires or two planar quantum wells separated by AlGaAs barriers ranging from 5.5 nm to 20 nm thickness is studied by photoluminescence and photoluminescence excitation spectroscopy. It is found that the transfer is strongly reduced between the widely spaced quantum wires as compared with quantum wells. This observation is supported by model calculations, which yield strong dimensionality dependence of the photon-exchange transfer

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44040 (URN)10.1063/1.2711757 (DOI)75475 (Local ID)75475 (Archive number)75475 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Lyo, S., Karlsson, F., Weman, H., Leifer, K., Rudra, A. & Kapon, E. (2006). Exciton Energy Transfer between Asymmetric Quantum Wires. In: APS March Meeting,2006.
Open this publication in new window or tab >>Exciton Energy Transfer between Asymmetric Quantum Wires
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2006 (English)In: APS March Meeting,2006, 2006Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44081 (URN)75521 (Local ID)75521 (Archive number)75521 (OAI)
Note
TalkAvailable from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
Reichardt, H., Leifer, K., Pelucchi, E., Karlsson, F., Weman, H., Rudra, A. & Kapon, E. (2006). Influence of long-range substrate roughness on disorder in V-groove quantum wire structures. Journal of Applied Physics, 100, 123509
Open this publication in new window or tab >>Influence of long-range substrate roughness on disorder in V-groove quantum wire structures
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2006 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, p. 123509-Article in journal (Refereed) Published
Abstract [en]

The observation and the interpretation of line splitting in photoluminescence and cathodoluminescence spectra of GaAs/AlGaAs V-groove quantum wires (QWRs) are reported. The QWR emission line splits into two peaks whose intensities oscillate systematically along the axis of the wire. Combining atomic force microscopy and cathodoluminescence measurements, we show a clear correlation between the surface topography of the V-groove and the individual peak intensities. We elucidate the relationship between the V-groove sidewall roughness and the shape at its bottom, and explain their impact on the QWR formation using a two-dimensional growth model accounting for self-limited growth in each V-groove domain. The influence of the long-range substrate roughness on the QWR spectral features is thus clarified. The study provides guidelines for improving QWR uniformity in order to achieve near-ideal model systems for one-dimensional semiconductors

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44034 (URN)10.1063/1.2401272 (DOI)75468 (Local ID)75468 (Archive number)75468 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Palmgren, S., Weman, H., Schoenberg, A., Karlsson, F., Rudra, A., Dupertuis, M.-A., . . . Kapon, E. (2006). Optical absorption spectra in V-groove quantum wires: Experiment and theory. In: Northern Optics,2006.
Open this publication in new window or tab >>Optical absorption spectra in V-groove quantum wires: Experiment and theory
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2006 (English)In: Northern Optics,2006, 2006Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44086 (URN)75527 (Local ID)75527 (Archive number)75527 (OAI)
Note
PosterAvailable from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
Palmgren, S., Weman, H., Schoenberg, A., Karlsson, F., Dupertuis, M.-A., Leifer, K., . . . Kapon, E. (2006). Polarization-resolved optical absorption in single V-groove quantum wires. Applied Physics Letters, 89, 191111
Open this publication in new window or tab >>Polarization-resolved optical absorption in single V-groove quantum wires
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2006 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 89, p. 191111-Article in journal (Refereed) Published
Abstract [en]

Optical transitions associated with all three linear polarization directions were investigated in single GaAs V-groove quantum wires of different wire thicknesses. This was accomplished by combining absorption measurements in V-groove waveguide geometry with surface-excited photoluminescence excitation spectroscopy. The observed transitions were identified with the aid of model calculations. It is shown that excitonic intersubband coupling should be accounted for in order to explain the optical transitions associated with confined light-hole-like states. The results are relevant for the design of efficient quantum wire waveguide modulators and lasers.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44035 (URN)10.1063/1.2386093 (DOI)75470 (Local ID)75470 (Archive number)75470 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Karlsson, F., Weman, H., Leifer, K., Rudra, A. & Kapon, E. (2004). Carrier tunneling between parallel GaAs/AlGaAs V-groove quantum wires. In: 27th International Conference on the Physics of Semiconductors ICPS-27,2004.
Open this publication in new window or tab >>Carrier tunneling between parallel GaAs/AlGaAs V-groove quantum wires
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2004 (English)In: 27th International Conference on the Physics of Semiconductors ICPS-27,2004, 2004Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44061 (URN)75497 (Local ID)75497 (Archive number)75497 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-01-23
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