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

Direct link
BETA
Alternative names
Publications (10 of 159) Show all publications
Chen, Y.-T., Karlsson, K. F., Birch, J. & Holtz, P.-O. (2016). Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy. Scientific Reports, 6(21482), 1-7.
Open this publication in new window or tab >>Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy
2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 21482, 1-7 p.Article in journal (Refereed) Published
Abstract [en]

Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2016
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-125803 (URN)10.1038/srep21482 (DOI)000370040800001 ()26876009 (PubMedID)
Note

Funding Agencies|Knut and Alice Wallenberg Foundation

Available from: 2016-03-08 Created: 2016-03-04 Last updated: 2017-11-30
Lazarev, M., Szeszko, J., Rudra, A., Karlsson, K. F. & Kapon, E. (2015). Parabolic tailored-potential quantum-wires grown in inverted pyramids. Journal of Crystal Growth, 414, 196-199.
Open this publication in new window or tab >>Parabolic tailored-potential quantum-wires grown in inverted pyramids
Show others...
2015 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 414, 196-199 p.Article in journal (Refereed) Published
Abstract [en]

Quasi-one-dimensional AlGaAs quantum wires (QWRs) with parabolic heterostructure profiles along their axis were fabricated using metallorganic vapor phase epitaxy (MOVPE) On patterned (111)B GaAs substrates. Tailoring of the confined electronic states via modification in the parabolic potential profile is demonstrated using model calculations and photoluminescence spectroscopy. These novel nanostructures are useful for studying the optical properties of systems with dimensionality between zero and one. (C) 2014 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
MOVPE; Patterned growth; Heterostructures; Low dimensional semiconductors; Quantum wires; Photoluminescence
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-115810 (URN)10.1016/j.jcrysgro.2014.11.008 (DOI)000349602900036 ()
Note

Funding Agencies|Swiss National Science Foundation [200020_156748]

Available from: 2015-03-20 Created: 2015-03-20 Last updated: 2017-12-04
Jemsson, T., Machhadani, H., Holtz, P.-O. & Karlsson, F. K. (2015). Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid. Nanotechnology, 26(6), 065702.
Open this publication in new window or tab >>Polarized single photon emission and photon bunching from an InGaN quantum dot on a GaN micropyramid
2015 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, no 6, 065702- p.Article in journal (Refereed) Published
Abstract [en]

We report on excitonic single photon emission and biexcitonic photon bunching from an InGaN quantum dot formed on the apex of a hexagonal GaN micropyramid. An approach to suppress uncorrelated emission from the pyramid base is proposed, a metal lm is demonstrated to eectively screen background emission and thereby signicantly enhance the signal-to-background ratio of the quantum dot emission. As a result, the second order coherence function at zero time delay g(2)(0) is signicantly reduced (to g(2)(0) = 0.24, raw value) for the excitonic autocorrelation at a temperature of 12 K under continuous wave excitation, and a dominating single photon emission is demonstrated to survive up to 50 K. The deterioration of the g(2)(0)-value at elevated temperatures is well understood as the combined eect of reduced signal-to-background ratio and limited time resolution of the setup. This result underlines the great potential of site controlled pyramidal dots as sources of fast polarized single photons.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113347 (URN)10.1088/0957-4484/26/6/065702 (DOI)000348448000018 ()
Available from: 2015-01-16 Created: 2015-01-16 Last updated: 2017-12-05Bibliographically approved
Karlsson, K. F., Oberli, D. Y., Dupertuis, M. A., Troncale, V., Byszewski, M., Pelucchi, E., . . . Kapon, E. (2015). Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking. New Journal of Physics, 17(10).
Open this publication in new window or tab >>Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking
Show others...
2015 (English)In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 17, no 10Article in journal (Refereed) Published
Abstract [en]

High symmetry epitaxial quantum dots (QDs) with three or more symmetry planes provide a very promising route for the generation of entangled photons for quantum information applications. The great challenge to fabricate nanoscopic high symmetry QDs is further complicated by the lack of structural characterization techniques able to resolve small symmetry breaking. In this work, we present an approach for identifying and analyzing the signatures of symmetry breaking in the optical spectra of QDs. Exciton complexes in InGaAs/AlGaAs QDs grown along the [111]B crystalline axis in inverted tetrahedral pyramids are studied by polarization resolved photoluminescence spectroscopy combined with lattice temperature dependence, excitation power dependence and temporal photon correlation measurements. By combining such a systematic experimental approach with a simple theoretical approach based on a point-group symmetry analysis of the polarized emission patterns of each exciton complex, we demonstrate that it is possible to achieve a strict and coherent identification of all the observable spectral patterns of numerous exciton complexes and a quantitative determination of the fine structure splittings of their quantum states. This analysis is found to be particularly powerful for selecting QDs with the highest degree of symmetry ( C 3 v and ##IMG## [http://ej.iop.org/images/1367-2630/17/10/103017/njp519062ieqn1.gif] $D_3h$ ) for potential applications of these QDs as polarization entangled photon sources. We exhibit the optical spectra when evolving towards asymmetrical QDs, and show the higher sensitivity of certain exciton complexes to symmetry breaking.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2015
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:liu:diva-123949 (URN)10.1088/1367-2630/17/10/103017 (DOI)000367329000006 ()
Note

Funding agencies: Swiss National Science Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

Available from: 2016-01-14 Created: 2016-01-14 Last updated: 2017-11-30Bibliographically approved
Klangtakai, P., Sanorpim, S., Karlsson, F., Holtz, P.-O., Pimanpang, S. & Onabe, K. (2014). Anomalous excitation-power-dependent photoluminescence of InGaAsN/GaAs T-shaped quantum wire. Physica Status Solidi (a) applications and materials science, 211(8), 1740-1744.
Open this publication in new window or tab >>Anomalous excitation-power-dependent photoluminescence of InGaAsN/GaAs T-shaped quantum wire
Show others...
2014 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 211, no 8, 1740-1744 p.Article in journal (Refereed) Published
Abstract [en]

The selected InGaAsN/GaAs T-shaped quantum wire (T-QWR) fabricated by metal organic vapor phase epitaxy has been investigated by microphotoluminescence (m-PL) and excitation-power-dependent mu-PL. The optical characteristics of one-dimensional structure were taken at low-temperature (4 K) and room temperature (RT) to clarify the intersection of two familiar quantum wells (QWs) in the [001] and [110] directions, named QW1 and QW2, respectively. For the excitation-power-dependent measurement, the intensity of the excitation source was used in the range of 0.001I(0) to I-0. The result shows that all of emissions related to QW1 and QWR peaks have a nonsymmetric line shape as evidenced by the tailing on the lower-energy side. All peaks shift to higher-energy side (blueshift) with the increase of the excitation power intensity. The blueshift and the low-energy tailing of PL peaks are attributed to the alloying effect. However, the emission peak related to QWR region shows a larger blueshift rate than that of QW1 on increasing of the excitation power intensity. This is an anomalous characteristic for the low-dimensional structure, affected by the large fluctuation state in the QWR region. This fluctuation state is combined of both edges of QWs (QW1 and QW2).

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2014
Keyword
GaAs; InGaAsN; MOVPE; photoluminescence; quantum wires
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-110487 (URN)10.1002/pssa.201330543 (DOI)000340521000010 ()
Note

Funding Agencies|Institute for Promotion of Teaching Science and Technology (IPST); National Nanotechnology Center (NANOTEC), NSTDA, Ministry of Science and Technology, Thailand, through its program of Center of Excellence Network; Thailand Research Fund [TRG5280030]; Thai Government Stimulus Package 2 under the project for Establishment of Comprehensive Center for Innovative Food, Health Products and Agriculture [TKK2555]

Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2017-12-05
Lundskog, A., Hsu, C.-W., Karlsson, K. F., Amloy, S., Nilsson, D., Forsberg, U., . . . Janzén, E. (2014). Direct generation of linearly-polarized photon emission with designated orientations from site-controlled InGaN quantum dots. Light: Science & Applications, 3, Article ID e139.
Open this publication in new window or tab >>Direct generation of linearly-polarized photon emission with designated orientations from site-controlled InGaN quantum dots
Show others...
2014 (English)In: Light: Science & Applications, ISSN 2095-5545, Vol. 3, e139Article in journal (Refereed) Published
Abstract [en]

Semiconductor quantum dots (QDs) have been demonstrated viable for the emission of single photons on demand during the past decade. However, the synthesis of QDs emitting photons with pre-defined and deterministic polarization vectors has proven arduous. The access of linearly-polarized photons is essential for various applications. In this report, a novel concept to directly generate linearly-polarized photons is presented. This concept is based on InGaN QDs grown on top of elongated GaN hexagonal pyramids, by which predefined orientations herald the polarization vectors of the emitted photons from the QDs. This growth scheme should allow fabrication of ultracompact arrays of photon emitters, with a controlled polarization direction for each individual QD emitter.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
Keyword
GaN; InGaN; photoluminescence; polarized emission; quantum dot
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-97417 (URN)10.1038/lsa.2014.20 (DOI)000331998400011 ()
Available from: 2013-09-12 Created: 2013-09-12 Last updated: 2017-04-11Bibliographically approved
Amloy, S., Karlsson, K. F., Eriksson, M. O., Palisaitis, J., Persson, P. O. Å., Chen, Y. T., . . . Holtz, P.-O. (2014). Excitons and biexcitons in InGaN quantum dot like localization centers. Nanotechnology, 25(49), 495702.
Open this publication in new window or tab >>Excitons and biexcitons in InGaN quantum dot like localization centers
Show others...
2014 (English)In: Nanotechnology, ISSN 0957-4484, Vol. 25, no 49, 495702- p.Article in journal (Refereed) Published
Abstract [en]

Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1–5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to −22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative Ebxx = −15.5 meV. 

Place, publisher, year, edition, pages
IOP Publishing, 2014
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-113334 (URN)10.1088/0957-4484/25/49/495702 (DOI)000345603800018 ()25410551 (PubMedID)
Available from: 2015-01-16 Created: 2015-01-16 Last updated: 2015-03-09
Jemsson, T., Machhadani, H., Karlsson, F. K., Hsu, C.-W. & Holtz, P.-O. (2014). Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot. Applied Physics Letters, 105(8), 081901-1-081901-4.
Open this publication in new window or tab >>Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot
Show others...
2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 8, 081901-1-081901-4 p.Article in journal (Refereed) Published
Abstract [en]

We report on the observation of linearly polarized single photon antibunching in the excitonic emission from a site-controlled InGaN quantum dot. The measured second order coherence function exhibits a significant dip at zero time difference, corresponding to g(m)(2) (0) = 0: 90 under continuous laser excitation. This relatively high value of g(m)(2) (0) is well understood by a model as the combination of short exciton life time (320 ps), limited experimental timing resolution and the presence of an uncorrelated broadband background emission from the sample. Our result provides the first rigorous evidence of InGaN quantum dot formation on hexagonal GaN pyramids, and it highlights a great potential in these dots as fast polarized single photon emitters if the background emission can be eliminated.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112065 (URN)10.1063/1.4893476 (DOI)000342753500022 ()
Note

Funding Agencies|Carl Trygger Foundation for Scientific Research; Swedish Research Council (VR); Nano-N consortium - Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Font-D, at Linkoping University

Available from: 2014-11-17 Created: 2014-11-13 Last updated: 2017-12-05Bibliographically approved
Urgessa, Z. N., Botha, J. R., Eriksson, M. O., Mbulanga, C. M., Dobson, S. R., Tankio Djiokap, S. R., . . . Holtz, P.-O. (2014). Low temperature near band edge recombination dynamics in ZnO nanorods. Journal of Applied Physics, 116(12), 123506.
Open this publication in new window or tab >>Low temperature near band edge recombination dynamics in ZnO nanorods
Show others...
2014 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 12, 123506- p.Article in journal (Refereed) Published
Abstract [en]

The recombination dynamics of neutral donor bound excitons ((DX)-X-o: I-4, I-6/6a) and near band edge defect-related emission in solution grown ZnO nanorods are investigated using steady state and time-resolved photoluminescence (PL) measurements. The effects of annealing are also studied. Low temperature steady state PL shows a systematic removal of the I-4 line after annealing at 450 degrees C and the subsequent domination of I-6a in these PL spectra. Additionally, the time decay of the I-4, I-6/6a, free exciton (FX), and basal plane stacking fault-related (BSF) PL transitions are studied as a function of annealing temperature. For the various annealing temperatures studied, the PL decay is described by a bi-exponential profile with a fast component (contribution from the surface) and slow component (related to bulk recombination). The fast component dominates in the case of as-grown and low temperature annealed samples (anneal temperatures up to 300 degrees C), suggesting the presence of surface adsorbed impurities. For samples annealed above 400 degrees C, the effects of the surface are reduced. The sample annealed at 850 degrees C produced an overall enhancement of the crystal quality. The underlying mechanisms for the observed PL characteristics are discussed based on near surface band bending caused by surface impurities.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-112055 (URN)10.1063/1.4896488 (DOI)000342840000018 ()
Note

Funding Agencies|South Africa Research Chairs Initiative of the Department of Science and Technology; National Research Foundation (NRF), South Africa; Nelson Mandela Metropolitan University (NMMU); Swedish-South Africa research collaboration

Available from: 2014-11-17 Created: 2014-11-13 Last updated: 2017-12-05
Dupertuis, M.-A., Karlsson, K. F., Oberli, D. Y., Dalessi, S., Gallinet, B. & Svendsen, G. (2014). Nanostructure symmetry: Relevance for physics and computing. In: : . Paper presented at ELECTRONIC, PHOTONIC, PLASMONIC, PHONONIC AND MAGNETIC PROPERTIES OF NANOMATERIALS (pp. 51-56). , 1590.
Open this publication in new window or tab >>Nanostructure symmetry: Relevance for physics and computing
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

We review the research done in recent years in our group on the effects of nanostructure symmetry, and outline its relevance both for nanostructure physics and for computations of their electronic and optical properties. The exemples of C3v and C2v quantum dots are used. A number of surprises and non-trivial aspects are outlined, and a few symmetry-based tools for computing and analysis are shortly presented.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-118677 (URN)10.1063/1.4870194 (DOI)978-0-7354-1222-4 (ISBN)
Conference
ELECTRONIC, PHOTONIC, PLASMONIC, PHONONIC AND MAGNETIC PROPERTIES OF NANOMATERIALS
Available from: 2015-06-03 Created: 2015-06-03 Last updated: 2015-06-17
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4547-6673

Search in DiVA

Show all publications