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  • 1.
    A Atlasov, Kirill
    et al.
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    Felici, Marco
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Gallo, Pascal
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    Rudra, Alok
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    Dwir, Benjamin
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    Kapon, Eli
    Ecole Polytech Fed Lausanne, Lab Phys Nanostruct, CH-1015 Lausanne, Switzerland .
    1D photonic band formation and photon localization in finite-size photonic-crystal waveguides2010Ingår i: OPTICS EXPRESS, ISSN 1094-4087, Vol. 18, nr 1, s. 117-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A transition from discrete optical modes to 1D photonic bands is experimentally observed and numerically studied in planar photonic-crystal (PhC) L-N microcavities of length N. For increasing N the confined modes progressively acquire a well-defined momentum, eventually reconstructing the band dispersion of the corresponding waveguide. Furthermore, photon localization due to disorder is observed experimentally in the membrane PhCs using spatially resolved photoluminescence spectroscopy. Implications on single-photon sources and transfer lines based on quasi-1D PhC structures are discussed.

  • 2.
    Adnane, Bouchaib
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hansson, Göran
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ni, Wei-Xin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Photoluminescence excitation spectroscopy of self-assembled SiGe/Si quantum dots2009Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Photoluminescence excitation (PLE) experiments are reported for various self-assembled SiGe/Si dot samples grown on Si(001) by molecular beam epitaxy at substrate temperatures ranging from 430 to 580 C. Two excitation peaks were observed, and the characteristics of the involved optical transitions were studied in detail by PLE (in one case implemented together with selective photoluminescence, SPL) on different samples containing either only one SiGe dot layer or multiple SiGe-dot/Si stacks. The temperature- and power-dependence of the excitation properties together with the results of six-band k.p calculations support the assignment of the observed PLE peaks to spatially direct and indirect transitions collected from two different SiGe dot populations.

  • 3.
    Adnane, Bouchaib
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hansson, Göran
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Ni, Wei-Xin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Spatially direct and indirect transitions of self-assembled SiGe/Si quantum dots studied by photoluminescence excitation spectroscopy2010Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, nr 18, s. 181107-Artikel i tidskrift (Refereegranskat)
    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.

  • 4.
    Adnane, Bouchaib
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Zhao, Ming
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Hansson, Göran
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Ni, Wei-Xin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Yt- och Halvledarfysik. Linköpings universitet, Tekniska högskolan.
    Origin of photoresponse at 8-14 μm in stacks of self-assembled SiGe/Si quantum dots2009Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235XArtikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    A normal incidence photodetector operating at 8-14 μm is demonstrated using p-type δ-doped SiGe dot multilayer structures grown by molecular beam epitaxy on Si(001) substrates. Based on the experimental results of photoluminescence and photoluminescence excitation spectroscopies together with numerical analysis, the origin of the measured photocurrent was attributed to intersubband optical transitions between the heavy hole and light hole states of the valence band of the self-assembled SiGe dots and subsequent lateral transport of photo-excited carriers in the conduction channels formed by Ge wetting layers.

  • 5.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Chen, Y T
    Acad Sinica, Taiwan .
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Chen, K H
    Acad Sinica, Taiwan .
    Hsu, H C
    National Taiwan University.
    Hsiao, C L
    National Taiwan University.
    Chen, L C
    National Taiwan University.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Polarization-resolved fine-structure splitting of zero-dimensional InxGa1-xN excitons2011Ingår i: PHYSICAL REVIEW B, ISSN 1098-0121, Vol. 83, nr 20, s. 201307-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fine-structure splitting of quantum confined InxGa1-x Nexcitons is investigated using polarization-sensitive photoluminescence spectroscopy. The majority of the studied emission lines exhibits mutually orthogonal fine-structure components split by 100-340 mu eV, as measured from the cleaved edge of the sample. The exciton and the biexciton reveal identical magnitudes but reversed sign of the energy splitting.

  • 6.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Andersson, T. G.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    On the polarized emission from exciton complexes in GaN quantum dots2012Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, nr 021901Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The optical linear polarization properties of exciton complexes in asymmetric Stranski-Krastanov grown GaN quantum dots have been investigated experimentally and theoretically. It is demonstrated that the polarization angle and the polarization degree can be conveniently employed to associate emission lines in the recorded photoluminescence spectra to a specific dot. The experimental results are in agreement with configuration interaction computations, which predict similar polarization degrees for the exciton and the biexciton (within 10%) in typical GaN quantum dots. The theory further predicts that the polarization degree can provide information about the charge state of the dot.

  • 7.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    III-nitride based quantum dots for photon emission with controlled polarization switchingManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Computational studies based on 6 band k⋅p!theory are employed on lens-shaped III-nitride quantum dots (QDs) with focus on the polarization properties of the optical interband transitions. The results predict pronounced linear polarization of the ground-state related transitions for asymmetric QDs of a material with small split-off energy. It is demonstrated that a moderate externally applied electric field can be used to induce a linear polarization and to control its direction. InN is found to be the most efficient choice for dynamic polarization switching controlled by an electric field, with potential for polarization control on a photon-by-photon level.

  • 8.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Chen, Y. T.
    Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan.
    Chen, K. H.
    Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan.
    Hsu, H. C.
    Center for Condensed Matter Sciences, National Taiwan University, Taiwan.
    Hsiao, C. L.
    Center for Condensed Matter Sciences, National Taiwan.
    Chen, L. C.
    Center for Condensed Matter Sciences, National Taiwan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Excitons and biexcitons in InGaN quantum dot like localization centersManuskript (preprint) (Övrigt vetenskapligt)
    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 justify the 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.

  • 9.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan. Thaksin University, Thailand.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Eriksson, Martin O
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Chen, Y. T.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan. Academia Sinica, Taiwan .
    Chen, K. H.
    Academia Sinica, Taiwan; National Taiwan University, Taiwan.
    Hsu, H. C.
    National Taiwan University, Taiwan.
    Hsiao, C. L.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. National Taiwan University, Taiwan.
    Chen, L. C.
    National Taiwan University, Taiwan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Excitons and biexcitons in InGaN quantum dot like localization centers2014Ingår i: Nanotechnology, ISSN 0957-4484, Vol. 25, nr 49, s. 495702-Artikel i tidskrift (Refereegranskat)
    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. 

  • 10.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Moskalenko, Evgenii
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Eriksson, M
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, K Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Chen, Y T
    Academic Sinica, Taiwan .
    Chen, K H
    Academic Sinica, Taiwan National Taiwan University, Taiwan .
    Hsu, H C
    National Taiwan University, Taiwan .
    Hsiao, C L
    National Taiwan University, Taiwan .
    Chen, L C
    National Taiwan University, Taiwan .
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot2012Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamics of the exciton and the biexciton related emission from a single InGaN quantum dot (QD) have been measured by time-resolved microphotoluminescence spectroscopy. An exciton-biexciton pair of the same QD was identified by the combination of power dependence and polarization-resolved spectroscopy. Moreover, the spectral temperature evolution was utilized in order to distinguish the biexciton from a trion. Both the exciton and the biexciton related emission reveal mono-exponential decays corresponding to time constants of similar to 900 and similar to 500 ps, respectively. The obtained lifetime ratio of similar to 1.8 indicates that the QD is small, with a size comparable to the exciton Bohr radius.

  • 11.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Yu, K. H.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Farivar, R
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden .
    Andersson, T. G.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden .
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Size dependent biexciton binding energies in GaN quantum dots2011Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 25, nr 251903Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single GaN/Al(Ga)N quantum dots (QDs) have been investigated by means of microphotoluminescence. Emission spectra related to excitons and biexcitons have been identified by excitation power dependence and polarization resolved spectroscopy. All investigated dots exhibit a strong degree of linear polarization (∼90%). The biexciton binding energy scales with the dot size. However, both positive and negative binding energies are found for the studied QDs. These results imply that careful size control of III-Nitride QDs would enable the emission of correlated photons with identical frequencies from the cascade recombination of the biexciton, with potential applications in the area of quantum information processing.

  • 12.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan. Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung, Thailand .
    Yu, K. H.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Karlsson, K Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Farivar, R.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S‐41296 Göteborg, Sweden.
    Andersson, T. G.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S‐41296 Göteborg, Sweden.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Polarized Emission from Single GaN Quantum Dots Grown by Molecular Beam Epitaxy2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Polarization resolved microphotoluminescence measurements of single MBE‐grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as <500 μeV  were observed. Interestingly, there exist both positive and negative binding energies of the biexciton, explained in term of different sizes of the measured dots, resulting in different built‐in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence‐band mixing induced by in‐plane anisotropy due to strain and/or QD shape.

  • 13.
    Amloy, Supaluck
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan. Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung, Thailand .
    Yu, K.H.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Farivar, R
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Andersson, Torwald
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Polarized Emission from Single GaN Quantum Dot Grown by Molecular Beam Epitaxy2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Polarization resolved microphotoluminescence measurements of single MBE‐grown GaN∕Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as <500 μeV were observed. Interestingly, there exist both positive and negative binding energies of the biexciton, explained in term of different sizes of the measured dots, resulting in different built‐in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence‐band mixing induced by in‐plane anisotropy due to strain and∕or QD shape.

  • 14.
    Atlasov, K. A.
    et al.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Surrente, A.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Calic, M.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Karlsson, K Fredrik
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Gallo, P.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Felici, Marco
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Dwir, Benjamin
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Rudra, Alok
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Kapon, E.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Site-controlled quantum-wire and quantum-dot photonic-crystal microcavity lasers2010Ingår i: Photonics Society Winter Topicals Meeting Series (WTM), 2010 IEEE, 2010, s. 149-150Konferensbidrag (Refereegranskat)
    Abstract [en]

    Based on site- and energy-controlled quantum wires (QWR) and quantum dots (QD), diverse photonic-crystal microcavity laser systems are proposed and discussed. Results demonstrating QWR lasing, cavity coupling and QD ordered arrays are presented.

  • 15. Atlasov, K.A.
    et al.
    Felici, M.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Gallo, P.
    Rudra, A.
    Dwir, B.
    Kapon, E.
    Tracking 1D photonic band formation in finite-size photonic crystal waveguides: disorder and localization effects2008Ingår i: 29th International Conference on the Physics of Semiconductors ICPS,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 16. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Deichsel, E.
    Dwir, B.
    Rudra, A.
    Kapon, E.
    Quantum Wire Lasers Utilizing Novel Optical Cavities2005Ingår i: EPFL Journee de la recherché,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 17.
    Atlasov, K.A.
    et al.
    Ecole Polytechnique Fédérale de Lausanne .
    Karlsson, Fredrik
    Ecole Polytechnique Fédérale de Lausanne .
    Deichsel, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Rudra, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Dwir, B.
    Ecole Polytechnique Fédérale de Lausanne .
    Kapon, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Site-controlled single quantum wire integrated into a photonic-crystal membrane microcavity2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, s. 153107-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Integration of a site-controlled semiconductor V-groove quantum wire (QWR) into a photonic-crystal (PhC) membrane microcavity is reported. Reproducible coupling of the QWR emission to a mode of the PhC cavity is evidenced by the narrower linewidth, higher intensity, and variation with temperature and PhC parameters of the QWR line. Finite difference time domain simulations of the cavity are employed for identifying the observed mode. The presented PhC-QWR coupled structures are promising for achieving very low-threshold lasers and for studies of one-dimensional photon-exciton coupled systems

  • 18.
    Atlasov, K.A.
    et al.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Gallo, P.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Rudra, A.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Dwir, B.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Kapon, E.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne, Lausanne.
    Observation of Stimulated Emission and Lasing in Quantum-wire Photonic-crystal Nanocavities2009Ingår i: IEEE/LEOS Winter Topical Meeting Series on Nanophotonics,2009, 2009Konferensbidrag (Övrigt vetenskapligt)
  • 19. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Gallo, P.
    Rudra, A.
    Dwir, B.
    Kapon, E.
    Quantum-Wire Lasers Based on Photonic-Crystal Nanocavities2008Ingår i: 17th International Laser Physics Workshop,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 20. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Kapon, E.
    Design of High-Q Membrane Photonic Crystal Defect Cavity for Integration with Semiconductor Quantum Wires2006Ingår i: 9th International conference on near-field optics, nanophotonics and related techniques NFO 9,2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 21. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Dwir, B.
    Kapon, E.
    Observation of Wavelength- and Loss-Splitting of Supermodes in Coupled Photonic-Crystal Microcavities2008Ingår i: Conference on Lasers and Electro-Optics CLEO,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 22. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Dwir, B.
    Kapon, E.
    Wavelength and loss splitting in directly coupled photonic-crystal defect microcavities2008Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 16, nr 20, s. 16255-16264Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coupling between photonic-crystal defect microcavities is observed to result in a splitting not only of the mode wavelength but also of the modal loss. It is discussed that the characteristics of the loss splitting may have an important impact on the optical energy transfer between the coupled resonators. The loss splitting - given by the imaginary part of the coupling strength - is found to arise from the difference in diffractive outof-plane radiation losses of the symmetric and the antisymmetric modes of the coupled system. An approach to control the splitting via coupling barrier engineering is presented. © 2008 Optical Society of America.

  • 23. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Kapon, E.
    1D Exciton-Photon Confinements in V-groove Quantum Wires Embedded into Photonic-Crystal Membrane Microcavities2007Ingår i: Second International Conference on One-dimensional Nanomaterials ICON 2007,2007, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 24. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Kapon, E.
    Integration of a Single V-groove Quantum Wire into 2D Photonic Crystal Membrane Microcavity2006Ingår i: 6th International Conference on Physics of Light-Matter Coupling in Nanostructures,2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 25.
    Atlasow, Kirill A.
    et al.
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Calic, Milan
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan. Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Gallo, Pascal
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Rudra, Alok
    n/Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Dwir, Benjamin
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Kapon, Eli
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Photonic-crystal microcavity laser with site-controlled quantum-wire active medium2009Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 17, nr 20, s. 18178-18183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Site-controlled quantum-wire photonic-crystal microcavity laser is experimentally demonstrated using optical pumping. The single-mode lasing and threshold are established based on the transient laser response, linewidth narrowing, and the details of the non-linear power input-output charateristics. Average-power threshold as low as ~240 nW (absorbed power) and spontaneous emission coupling coefficient β~0.3 are derived.

  • 26. Baier, M.H.
    et al.
    Malko, A.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Pelucchi, E.
    Kapon, E.
    Electrical and optical excitation schemes for pyramidal quantum dot single photon emitters2005Ingår i: Conference in Lasers and Electro-Optics CLEO,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 27. Baier, M.H.
    et al.
    Malko, A.
    Pelucchi, E.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Oberli, D.Y.
    Kapon, E.
    Single photon emitters based on InGaAs/AlGaAs quantum dots grown by MOVPE in inverted pyramids2005Ingår i: 11th European Workshop on MOVPE,2005, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 28. Byszewski, M.
    et al.
    Chalupar, B.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Oberli, D.Y.
    Pelucchi, E.
    Rudra, A.
    Kapon, E.
    Magneto-photoluminescence of heavy- and light-hole excitons in site-controlled pyramidal quantum dots2007Ingår i: 13th International Conference Modulated Semiconductor Structures MSS 13,2007, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 29.
    Byszewski, M.
    et al.
    Ecole Polytechnique Fédérale de Lausanne .
    Chalupar, B.
    Ecole Polytechnique Fédérale de Lausanne .
    Karlsson, Fredrik
    Ecole Polytechnique Fédérale de Lausanne .
    Oberli, D.Y.
    Ecole Polytechnique Fédérale de Lausanne .
    Pelucchi, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Rudra, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Kapon, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Magneto-photoluminescence of heavy- and light-hole excitons in site-controlled pyramidal quantum dots2008Ingår i: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 40, nr 6, s. 1873-1875Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pyramidal, site-controlled InGaAs/AlGaAs quantum dots (QDs) are studied by micro-photoluminescence (PL) spectroscopy in a magnetic field. The light-hole (LH) excitonic transitions exhibit diamagnetic shifts similar to those of their heavy-hole (HH) counterparts. From the evolution of the excitonic lines, effective g-factors of g=1.7 and 0.4 for HH and LH neutral excitons are inferred

  • 30.
    Chalangar, Ebrahim
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Halmstad Univ, Sweden.
    Machhadani, Houssaine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Lim, Seung-Hyuk
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. Halmstad Univ, Sweden; Lund Univ, Sweden; Lund Univ, Sweden.
    Influence of morphology on electrical and optical properties of graphene/Al-doped ZnO-nanorod composites2018Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 29, nr 41, artikel-id 415201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of future 3D-printed electronics relies on the access to highly conductive inexpensive materials that are printable at low temperatures (amp;lt;100 degrees C). The implementation of available materials for these applications are, however, still limited by issues related to cost and printing quality. Here, we report on the simple hydrothermal growth of novel nanocomposites that are well suited for conductive printing applications. The nanocomposites comprise highly Al-doped ZnO nanorods grown on graphene nanoplatelets (GNPs). The ZnO nanorods play the two major roles of (i) preventing GNPs from agglomerating and (ii) promoting electrical conduction paths between the graphene platelets. The effect of two different ZnO-nanorod morphologies with varying Al-doping concentration on the nanocomposite conductivity and the graphene dispersity are investigated. Time-dependent absorption, photoluminescence and photoconductivity measurements show that growth in high pH solutions promotes a better graphene dispersity, higher doping levels and enhanced bonding between the graphene and the ZnO nanorods. Growth in low pH solutions yields samples characterized by a higher conductivity and a reduced number of surface defects. These samples also exhibit a large persistent photoconductivity attributed to an effective charge separation and transfer from the nanorods to the graphene platelets. Our findings can be used to tailor the conductivity of novel printable composites, or for fabrication of large volumes of inexpensive porous conjugated graphene-semiconductor composites.

  • 31.
    Chen, Yen-Ting
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, nr 21482, s. 1-7Artikel i tidskrift (Refereegranskat)
    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.

  • 32. Donchev, V.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Kirilov, K.
    Ivanov, Ts.
    Germanova, K.
    Saraydarov, M.
    Electronic states of V-shapes quantum wires with graded interfaces2007Ingår i: 9th Workshop on Nanoscience and Nanotechnology,2007, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 33. Donchev, V.
    et al.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Moskalenko, Evgenii
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Holtz, Per-Olof
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Schoenfeld, J.M.
    Garcia, J.M.
    Petroff, M.
    Temperature Study of the Photoluminescence of a Single InAs/GaAs Quantum Dot2004Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 3, s. 608-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Presented at: The 8th Conference on Optics of Excitons in Confined Systems, Lecce, Italy, February 3 - 4, 2003

  • 34.
    Dufåker, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Fredrik, Karlsson
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Mereni, L O.
    National University of Ireland University of Coll Cork, Ireland .
    Dimastrodonato, V
    National University of Ireland University of Coll Cork, Ireland .
    Juska, G
    National University of Ireland University of Coll Cork, Ireland .
    Pelucchi, E
    National University of Ireland University of Coll Cork, Ireland .
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Evidence of nonadiabatic exciton-phonon interaction probed by second-order LO-phonon replicas of single quantum dots2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, nr 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this experimental study of single InGaAs/GaAs quantum dots (QDs) the photoluminescence intensity of the second order LO-phonon replica of the excitonic interband recombination was measured along with the intensities of the first and zeroth orders. The results show that the intensity of the second-order replica is three to four times stronger than expected from the adiabatic Huang-Rhys theory, indicating that the neglected nonadiabaticity plays an important role for the understanding of the exciton-phonon coupling in QDs.

  • 35.
    Dufåker, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Dimastrodonato, V
    Tyndall National Institute, University College Cork, Ireland.
    O Mereni, L
    Tyndall National Institute, University College Cork, Ireland.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pelucchi, E
    Tyndall National Institute, University College Cork, Ireland.
    Phonon replicas of charged and neutral exciton complexes in single quantum dots2010Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, nr 20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The longitudinal-optical (LO)-phonon coupling is experimentally examined by the optical decay of various charged and neutral exciton species in single quantum dots, and the related Huang-Rhys parameters are extracted. A positive trion exhibits significantly weaker LO-phonon replicas in the photoluminescence spectrum than the neutral and negatively charged species. Model computations show that the strength of the replicas is determined by the Coulomb interactions between electrons and holes, which modify the localization of the envelope wave functions and the net charge distribution.

  • 36.
    Dufåker, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet.
    Pelucchi, E.
    Cork Univ. Ireland.
    Phonon Coupling of Exciton Complexes in Single InGaAs/AlGaAs Quantum Dots2010Konferensbidrag (Refereegranskat)
  • 37.
    Dufåker, Daniel
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Mereni, L. O.
    Epitaxy and Physics of Nanostructures, Tyndall National Institute, University College Cork, Dyke Parade, Cork, Ireland.
    Dimastrodonato, V.
    Tyndall National Institute, University College Cork, Dyke Parade, Cork, Ireland.
    Juska, G.
    Tyndall National Institute, University College Cork, Ireland.
    Pelucchi, E.
    Tyndall National Institute, University College Cork, Dyke Parade, Cork, Ireland.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Quantum dot asymmetry and the nature of excited hole states probed by the doubly positively charged exciton X2+2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this experimental and theoretical study, it was found that the emission pattern of the doubly positively charged exciton complex X2+ strongly depends on the nature of the involved excited hole states as well as the quantum dot symmetry. The two-hole system in the final state of the X2+ recombination for the investigated high-symmetry pyramidal InGaAs quantum dots does not exhibit the singlet-tripletlike arrangement previously observed for the two-electron counterpart. Instead, the final states exhibit two true doublets, in accordance with group-theoretical predictions. Asymmetry is manifested in the photoluminescence spectra of X2+ by a significant splitting of one doublet, which is a spectral feature exhibited to some degree by all of the measured quantum dots. The analysis demonstrates that an external magnetic field elevates the symmetry of the quantum dots. This work highlights the exciton complex X2+ as a very sensitive probe of the quantum dot shape as well as the nature of the involved quantum states. Thus, its spectral features are very suitable for an efficient uninvasive postgrowth symmetry characterization of quantum dots.

  • 38.
    Dufåker, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Mereni, L. O.
    Tyndall National Institute, University College Cork, Ireland.
    Karlsson, Fredrik K.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Dimastrodonato, V.
    Tyndall National Institute, University College Cork, Ireland.
    Juska, G.
    Tyndall National Institute, University College Cork, Ireland.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Pelucchi, E.
    Tyndall National Institute, University College Cork, Ireland.
    Exciton-phonon coupling in single quantum dots with different barriers2011Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 25, s. 251911-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The coupling between longitudinal-optical (LO) phonons and neutral excitons in two different kinds of InGaAs pyramidal quantum dots embedded in either AlGaAs or GaAs barriers is experimentally examined. We find a slightly weaker exciton-LO-phonon coupling and increased linewidth of the phonon replicas for the quantum dots with GaAs barriers compared to the ones with AlGaAs barriers. These results, combined with the fact that the LO-phonon energy of the exciton is the same for both kinds of dots, are taken as evidence that the excitons mainly couple to LO-phonons within the QDs.

  • 39.
    Dupertuis, M A
    et al.
    Ecole Polytech Fed Lausanne.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Oberli, D Y
    Ecole Polytech Fed Lausanne.
    Pelucchi, E
    Ecole Polytech Fed Lausanne.
    Rudra, A
    Ecole Polytech Fed Lausanne.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kapon, E
    Ecole Polytech Fed Lausanne.
    Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots2011Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, nr 12, s. 127403-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, and predict original features for low C(2 nu) and high C(3 nu) symmetries. Excellent agreement with single quantum dot spectroscopy of real pyramidal InGaAs/AlGaAs quantum dots grown along [111] is demonstrated. The high sensitivity of biexciton quantum states to exact high symmetry can be turned into an efficient uninvasive postgrowth selection procedure for quantum entanglement applications.

  • 40.
    Dupertuis, Marc-André
    et al.
    Laboratory of Physics of Nanostructure, EPF Lausanne, Switzerland.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Oberli, D. Y.
    Laboratory of Physics of Nanostructure, EPF Lausanne, Switzerland.
    Dalessi, S.
    Laboratory of Physics of Nanostructure, EPF Lausanne, Switzerland.
    Gallinet, B.
    Nanophotonics and Metrology Laboratory, EPF Lausanne, Switzerland.
    Svendsen, G.
    Dept. of Electronics and Telecom., Norwegian University of Science and Technology, Trondheim, Norway.
    Nanostructure symmetry: Relevance for physics and computing2014Konferensbidrag (Refereegranskat)
    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.

  • 41.
    Eriksson, Martin. O.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lundskog, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Bergman, Peder
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    The Dynamics of Charged and Neutral Excitons in an InGaN Quantum Dot on a GaN PyramidManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The neutral (X0) and negatively charged excitons (X-) in an InGaN QD on a GaN pyramid is studied by the timeintegrated micro-photoluminescence (μPL) and time-resolved micro-photoluminescence (TRμPL) microcopies. Both X0 and X- exhibit mono-exponential decay curves with fitted lifetimes of 310 and 140 ps, respectively. Neither energy shifts nor changes in the life times X0 and X- with increasing excitation power were observed, indicating the QD is small and free from the quantum confine Stark effect. The TRμPL is not only a powerful technique for studying the dynamics of exciton in QDXs, but also for the identification of exciton complexes in QDs.

  • 42. Felici, M.
    et al.
    Gallo, P.
    Mohan, A.
    Dwir, B.
    Atlasov, A.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Biasiol, G.
    Sorba, L.
    Kapon, E.
    Deterministic incorporation of pyramidal quantum dots in photonic crystal cavities2008Ingår i: The 5th International Conerence on Semiconductor Quantum Dots QD2008,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 43.
    Gallo, P.
    et al.
    Ecole Polytechnique Fédérale de Lausanne .
    Felici, M.
    Ecole Polytechnique Fédérale de Lausanne .
    Dwir, B.
    Ecole Polytechnique Fédérale de Lausanne .
    Atlasov, K.A.
    Ecole Polytechnique Fédérale de Lausanne .
    Karlsson, Fredrik
    Ecole Polytechnique Fédérale de Lausanne .
    Rudra, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Mohan, A.
    Ecole Polytechnique Fédérale de Lausanne .
    Biasiol, G.
    TASC INFM-CNR.
    Sorba, L.
    NEST INFM-CNR and Scuola Normale Superiore.
    Kapon, E.
    Ecole Polytechnique Fédérale de Lausanne .
    Integration of site-controlled pyramidal quantum dots and photonic crystal membrane cavities2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, s. 263101-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors demonstrate the deterministic coupling between a single, site-controlled InGaAs/GaAs pyramidal quantum dot (QD) and a photonic crystal membrane cavity defect. The growth of self-ordered pyramidal QDs in small (300 nm base side) tetrahedral recesses etched on (111)B GaAs substrates was developed in order to allow their integration within the thin GaAs membranes. Accurate (better than 50 nm) positioning of the QD with respect to the optical cavity mode is achieved reproducibly owing to the site control. Coupling of the dot emission with the cavity mode is evidenced in photoluminescence measurements. The deterministic positioning of the pyramidal QDs and the control of their emission spectrum opens the way for devices based on QDs integrated with coupled nanocavities.

  • 44. Gallo, P.
    et al.
    Felici, M.
    Dwir, B.
    Atlasov, K.A.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Rudra, A.
    Mohan, A.
    Kapon, E.
    Biasiol, G.
    Sorba, L.
    Integration of Site-Controlled Pyramidal Quantum Dots and Photonic Crystal Membrane Cavities2008Ingår i: Conference on Lasers and Electro-Optics CLEO,2008, 2008Konferensbidrag (Övrigt vetenskapligt)
  • 45.
    Hirasaki, Takahide
    et al.
    Tokyo University of Agriculture and Technology, Japan.
    Eriksson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Tu Thieu, Quang
    Tokyo University of Agriculture and Technology, Japan.
    Karlsson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Murakami, Hisashi
    Tokyo University of Agriculture and Technology, Japan.
    Kumagai, Yoshinao
    Tokyo University of Agriculture and Technology, Japan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Tokyo University of Agriculture and Technology, Japan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Koukitu, Akinori
    Tokyo University of Agriculture and Technology, Japan.
    Growth of thick and high crystalline quality InGaN layers on GaN (000(1)over-bar) substrate using tri-halide vapor phase epitaxy2016Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 456, s. 145-150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growth of thick InGaN layers on free-standing GaN (000 (1) over bar substrates was studied using tri-halide vapor phase epitaxy. It was found that high-indium-content InGaN can be grown under higher InCl3 input partial pressure at higher growth temperature, which allows the fabrication of a high crystalline quality InGaN layer with a smooth surface morphology. Using the growth conditions of high InCl3 input partial pressure and high growth temperature, crack- and droplet-free InGaN layers with a thickness of over 10 mu m and with an indium fraction of 0.05 were successfully grown. Although the surface showed many hillocks, the number of hillocks was reduced upon growth of thicker InGaN layers. Photoluminescence measurements confirm that thick InGaN layers could be successfully grown without degradation of the crystalline quality. (C) 2016 Elsevier B.V. All rights reserved.

  • 46.
    Holtz, Per Olof
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hsu, Chi-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lundskog, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, K. Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Deterministic Single InGaN Quantum Dots grown on GaN Micro-Pyramid Arrays2013Ingår i: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 646, s. 34-37Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    InGaN quantum dots (QDs) formed on top of GaN pyramids have been fabricated by means of selective area growth employing hot wall MOCVD. Upon regrowth of a patterned substrate, the growth will solely occur in the holes, which evolve into epitaxially grown wurtzite based pyramids. These pyramids are subsequently overgrown by a thin optically active InGaN well. The QDs are preferably nucleating at the apices of the pyramids as evidenced by the transmission electron microscopy (TEM). The emission from these QDs have been monitored by means of microphotoluminescence (µPL), in which single emission lines have been detected with a sub-meV line width. The µPL measurements undoubtedly reveal that the QDs are located in the apexes of the pyramids, since the sharp emission peaks can only be monitored as the excitation laser is focused on the apices in the µPL. It is also demonstrated that the emission energy can be changed in a controlled way by altering the growth conditions, like the growth temperature and/or composition, for the InGaN layers. The tip of the GaN pyramid is on the nm scale and can be made sharp or slightly truncated. TEM analysis combined with µPL results strongly indicate that the Stranski-Krastanow growth modepreferably is taking place at the microscopic c-plane truncation of the GaN pyramid. Single emission lines with a high degree of polarization is a common feature observed for individual QDs. This emission remains unchanged with increasing the excitation power and sample temperature. An in-plane elongated QD forming a shallow potential with an equal number of electrons and holes is proposed to explain the observed characteristics of merely a single exciton emission with a high degree of polarization.

  • 47.
    Holtz, Per-Olof
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Larsson, L A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Karlsson, K Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Dufåker, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Lundskog, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Moskalenko, Evgenii
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dimastrodonato, V
    National University of Ireland University of Coll Cork.
    Mereni, L
    National University of Ireland University of Coll Cork.
    Pelucchi, E
    National University of Ireland University of Coll Cork.
    Optical characterization of individual quantum dots2012Ingår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 407, nr 10, s. 1472-1475Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Optical characterization of single quantum dots (QDs) by means of micro-photoluminescence (mu PL) will be reviewed. Both QDs formed in the Stranski-Krastanov mode as well as dots in the apex of pyramidal structures will be presented. For InGaAs/GaAs dots, several excitonic features with different charge states will be demonstrated. By varying the magnitude of an external electric or magnetic field and/or the temperature, it has been demonstrated that the transportation of carriers is affected and accordingly the charge state of a single QD can be tuned. In addition, we have shown that the charge state of the QD can be controlled also by pure optical means, i.e. by altering the photo excitation conditions. Based on the experience of the developed InAs/GaAs QD system, similar methods have been applied on the InGaN/GaN QD system. less thanbrgreater than less thanbrgreater thanThe coupling of LO phonons to the QD emission is experimentally examined for both charged and neutral excitons in single InGaAs/GaAs QDs in the apex of pyramidal structures. It is shown that the positively charged exciton exhibits a significantly weaker LO phonon coupling in the mu PL spectra than the neutral and negatively charged species, a fact, which is in consistency with model simulations performed.

  • 48.
    Holtz, Per-Olof
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Moskalenko, ES
    Larsson, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Schoenfeld, WV
    Petroff, PM
    Enhanced Luminescence from Single InAs/GaAs Quantum Dots2007Ingår i: NSTI Nanotech, Nanostructured Materials Devices,2007, 2007Konferensbidrag (Refereegranskat)
  • 49.
    Holtz, Per-Olof
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Moskalenko, Evgenii
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Larsson, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Schoenfeld, W.V.
    Petroff, P.M.
    Effects of External Fields on the Excitonic Emission from Single InAs/GaAs Quantum Dots2008Ingår i: Microelectronics Journal, Vol. 39, Microelectronics Journal: Elsevier , 2008, s. 331-334Konferensbidrag (Refereegranskat)
    Abstract [en]

    A low-temperature micro-photoluminescence (μ-PL) investigation of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field is reported. It is demonstrated that the QDs PL signal could be increased several times by altering the external and/or the internal electric field. The internal field in the vicinity of the dots could be altered by means of an additional infra-red laser. We propose a model, which is based on an essentially faster lateral transport of the charge carriers achieved in an external electric field. Consequently, also the capture probability into the dots and subsequently the dot luminescence is also enhanced. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity measured in our experiment.

  • 50.
    Holtz, Per-Olof
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Moskalenko, Evgenii
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Larsson, Mats
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Karlsson, Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Schoenfeld, W.V.
    Petroff, P.M.
    Electric Field Induced Enhancement of the Luminescence from Single InAs/GaAs Quantum Dots2007Ingår i: The 7th Conference on the Physics of Light Matter Coupling in Nanostructures PLMCN7,2007, 2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

      

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