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  • 1.
    Adnane, Bouchaib
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Zhao, Ming
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Magnuson, Bengt
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Mid/far-infrared detection using a MESFET with B-modulation doped Ge-dot/SiGe-well multiple stacks in the channel region2004Conference paper (Refereed)
    Abstract [en]

    Multiple modulation-doped Ge-dot/SiGe-QW stack structures were grown using MBE, and processed as FET devices for mid/far infrared detection. From a non-optimized device, a broadband photoresponse has been observed in the mid-infrared range of 3-15 μm. A peak responsivity was estimated to be as high as 100 mA/W at T= 20 K. This work indicates that SiGE QD/QW structures using the lateral transport geometry can be a potential candidate for photodetectors operating in far-infrared range.

  • 2.
    Elfving, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Hansson, Göran V.
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Efficient near infrared Si/Ge quantum dot photodetector based on a heterojunction bipolar transistor2003In: Material Research Society Symposium Proceedings, 2003, Vol. 770Conference paper (Refereed)
  • 3. Gomes, P F
    et al.
    Cerdeira, F
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Madureira, J R
    García-Cristóbal, A
    Large optical emission blue shift in Ge/Si quantum dots under external biaxial strain2008In: ICPS 29th International Conference on the Physics of Semiconductors,2008, 2008Conference paper (Refereed)
  • 4. Gomes, P.F.
    et al.
    Gomes, P.F.
    Iikawa, F.
    Iikawa, F.
    Cerdeira, F.
    Cerdeira, F.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Size dependent spatial direct and indirect transitions in Ge/Si QDs2007In: The 6th International Conference on Low Dimensional Structures and Devices,2007, 2007Conference paper (Refereed)
  • 5.
    Gomes, P.F.
    et al.
    Intituto de Física Gleb Wataghin, Unicamp, CP 6165, Campinas, São Paulo 13083-970, Brazil.
    Iikawa, F.
    Intituto de Física Gleb Wataghin, Unicamp, CP 6165, Campinas, São Paulo 13083-970, Brazil.
    Cerdeira, F.
    Intituto de Física Gleb Wataghin, Unicamp, CP 6165, Campinas, São Paulo 13083-970, Brazil.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Type-I optical emissions in GeSi quantum dots2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 5Article in journal (Refereed)
    Abstract [en]

    The authors studied the optical emission of GeSi quantum dots under externally applied biaxial stress using samples grown with different temperatures varying from 430 to 700 °C. The optical emission energy of samples grown at low temperatures is rather insensitive to the applied external stress, consistent with the type-II band alignment. However, for samples grown at high temperatures we observed a large blueshift, which suggests type-I alignment. The result implies that recombination strength can be controlled by the growth temperature, which can be useful for optical device applications. © 2007 American Institute of Physics.

  • 6.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, ES
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, WV
    Petroff, PM
    Enhanced Luminescence from Single InAs/GaAs Quantum Dots2007In: NSTI Nanotech, Nanostructured Materials Devices,2007, 2007Conference paper (Refereed)
  • 7.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgeni
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, K.F.
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhanced Luminescence from InAs/GaAs Quantum Dots2006In: Optical Materials in Defence Systems Technology III,2006, Proceedings of SPIE 6401: SPIE Digital Library , 2006, p. 64010I-Conference paper (Refereed)
  • 8.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Schoenfeld, W.V.
    Petroff, P.M.
    Effects of External Fields on the Excitonic Emission from Single InAs/GaAs Quantum Dots2008In: Microelectronics Journal, Vol. 39, Microelectronics Journal: Elsevier , 2008, p. 331-334Conference paper (Refereed)
    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.

  • 9.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Electric Field Induced Enhancement of the Luminescence from Single InAs/GaAs Quantum Dots2007In: The 7th Conference on the Physics of Light Matter Coupling in Nanostructures PLMCN7,2007, 2007Conference paper (Other academic)
    Abstract [en]

      

  • 10.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhanced Luminescence from Self-Assembled Quantum Dots2006In: The International Conference on Nanoscience and Technology ICNT 2006,2006, 2006Conference paper (Other academic)
  • 11.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhanced Luminescence from Self-Assembled Quantum Dots2006In: 14th Interenational School on Condensed Matter Physics,2006, 2006Conference paper (Other academic)
  • 12.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhancement of the Luminescence from Single InAs/GaAs Quantum Dots by Application of an Electric Field2007In: Nanotech Northern Europe 2007,2007, 2007Conference paper (Other academic)
    Abstract [en]

       

  • 13.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhancement of the Luminescence from Single InAs/GaAs Quantum Dots by Application of an Electric Field2007In: The Quantum Dot Meeting,2007, 2007Conference paper (Other academic)
    Abstract [en]

       

  • 14.
    Holtz, Per-Olof
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Optical Properties of Self-Assembled Quantum Dots2006In: Scientific INTAS-SB RAS Workshop,2006, 2006Conference paper (Other academic)
  • 15.
    Karim, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Hansson, G. V.
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Compositional analysis of Si/SiGe quantum dots using STEM and EDX2006In: Volume 6129 - Quantum Dots, Particles, and Nanoclusters III, Proceedings of SPIE, 2006Conference paper (Refereed)
    Abstract [en]

    Ge islands fabricated on Si(100) by molecular beam epitaxy at different growth temperatures, were studied using crosssectional scanning transmission electron microscopy and energy-dispersive X-ray spectrometry combined with electron energy loss spectrometry experiments. The island size, shape, strain, and material composition define the dot-related optical transition energies, but they are all strongly dependent on the growth temperature. We have performed quantitative investigations of the material composition of Ge/Si(001) quantum dots. The samples were grown at temperatures ranging from 430 to 730 °C, with one buried and one uncapped layer of Ge islands separated by 140 nm intrinsic Si. The measurements showed a Ge concentration very close to 100 % in the islands of samples grown at 430 °C. With a growth temperature of 530 °C, a ~20 % reduction of the Ge fraction was observed, which is due to intermixing of Si and Ge. This is consistent with our previous photoluminescence results, which revealed a significant blue shift of the Ge dot-related emission peak in this growth temperature range. The Ge concentration decreases more slowly when the growth temperature is increased above 600 °C, which can be explained by geometrical arguments. The longer distance between the interface and the core of these larger sized dome-shaped islands implies that less Si atoms reach the dot center. In general, the uncapped Ge dots have similar widths as the embedded islands, but the height is almost exclusively larger. Furthermore, the Ge concentration is slightly lower for the overgrown dots.

  • 16.
    Karim, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hansson, G. V.
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics . Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Atwater, H.A.
    Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
    Photoluminescence Studies of Sn Quantum Dots in Si Grown by MBE2005In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 27, no 5, p. 836-840Article in journal (Refereed)
    Abstract [en]

    A few nanometer thick SnxSi1−x layers with x 0.1 grown on silicon (1 0 0) surfaces can be used to form tin (α-Sn) quantum dots as a result of heat treatment of such structures up to 800 °C. These quantum dots with a well-defined shape are expected to be a candidate for obtaining a low-energy direct band gap structure in Si. Absorption measurements reported by Ragan et al. have shown the onset of absorption at 0.27 eV indicating that the MBE-grown α-Sn quantum dots could be used, e.g. in infrared detectors or emitters. We have performed low temperature photoluminescence (PL) studies of some of the structures produced in this first study and observed no emission peak near 0.27 eV. The PL spectra are instead characterised by a broadband emission in the range 0.7–1 eV. Furthermore there are narrow features that have previously been described as the 789 meV C–O band and 1018 meV W or I1 band. The broad emission at 0.7–1 eV is attributed to the presence of defects introduced by the grown layers, which have suppressed the emission peaks related to the substrate as well. We have also grown α-Sn quantum dot samples on Si (1 0 0) substrates with very low doping concentrations. These samples show PL spectra with Si-substrate related peaks and a relatively lower broad feature at 0.7–1 eV. However, no emission was observed near 0.27 eV.

  • 17.
    Larsson, Arvid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, E.S.
    Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russian Federation.
    Magnetic field enabled charge state control of single InAs/GaAs quantum dots2009In: 2009 9th IEEE Conference on Nanotechnology, IEEE NANO 2009, 2009, p. 510-512Conference paper (Refereed)
    Abstract [en]

    Micro-photoluminescence in the presence of an external magnetic field is employed to study individual InAs/GaAs quantum dots (QDs). By varying the strength of the applied magnetic field, the charge state of the QD is tuned from a double negatively charged exciton to a neutral exciton. This effect is shown to be related to carrier transport in the QD-plane prior to capture into the QD. The temperature dependence of the tuning effect is discussed. © 2009 IEEE NANO Organizers.

  • 18.
    Larsson, Arvid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Moskalenko, E
    Ioffe Inst.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Effective tuning of the charge state of a single InAs/GaAs quantum dot by means of external fields2009In: IEEE Nano 2009 in Genua, 2009Conference paper (Refereed)
  • 19.
    Larsson, Arvid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Moskalenko, E
    n/a.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Tuning of the charge state of a single InAs/GaAs quantum dot by means of external fields2009In: Nordic Semiconductor Meeting, Reykavik, 2009Conference paper (Refereed)
  • 20.
    Larsson, Arvid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Moskalenko, Evgenii
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Charge state control of single InAs/GaAs quantum dots by means of an external magnetic field2008In: in PHYSICS OF SEMICONDUCTORS, vol 1199, AIP , 2008, p. 297-298Conference paper (Refereed)
    Abstract [en]

    Individual InAs/GaAs quantum dots (QDs) are studied with micro-photoluminescence in the presence of an applied external magnetic field. Attention is focused on the redistribution between the spectral lines of a single QD observed at increased external magnetic field when the magnetic field is applied parallel to the growth direction (Faraday geometry). The effect is shown to be transport related as the electron drift velocity in the QD-plane is decreased by the applied magnetic field and this affects the probability for electron capture into the QD.

  • 21.
    Larsson, Arvid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Tuning of the charge state of InAs/GaAs quantum dot by a magnetic field2007In: Nordic Semiconductor Meeting, NSM22,2007, 2007Conference paper (Other academic)
    Abstract [en]

      

  • 22.
    Larsson, Arvid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgeny
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Charge state tuning of individual InAs/GaAs quantum dots by an external magnetic field2008In: 8th International Conference on Physics of Light-Matter Coupling in nanostructures PLMCN8,2008, 2008Conference paper (Other academic)
  • 23.
    Larsson, Arvid
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgeny
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Tuning of the charge state of individual InAs/GaAs quantum dots by an external magnetic field2008In: The 5th International Conference on Semiconductor Quantum Dots QD2008,2008, 2008Conference paper (Other academic)
  • 24.
    Larsson, L. Arvid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, E. S.
    Russian Academy of Science.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Temperature and Magnetic Field Effects on the Transport Controlled Charge State of a Single Quantum Dot2010In: NANOSCALE RESEARCH LETTERS, ISSN 1931-7573, Vol. 5, no 7, p. 1150-1155Article in journal (Refereed)
    Abstract [en]

    Individual InAs/GaAs quantum dots are studied by micro-photoluminescence. By varying the strength of an applied external magnetic field and/or the temperature, it is demonstrated that the charge state of a single quantum dot can be tuned. This tuning effect is shown to be related to the in-plane electron and hole transport, prior to capture into the quantum dot, since the photo-excited carriers are primarily generated in the barrier.

  • 25.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Spectroscopy of semiconductor quantum dots2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantum dots in the Si/Ge and InAs/GaAs materials systems are examined by means of photoluminescence. The spectroscopic study of Si/Ge quantum dots has demonstrated two different radiative recombination channels in the type II band alignment: The spatially direct transition inside the dot and the spatially indirect transition across the dot interface. Increased sample temperature results in a gradual transfer from the spatially indirect to the spatially direct recombination due to higher oscillator strength combined with the increased electron population inside the dot. In contrast to the spatially direct transition, the spatially indirect transition is shown to be sensitive to the carrier density due to the band bending at the Si/Ge interface. Due to an increased Si/Ge intermixing and hence reduced strain in the Si barrier, a reduction of the conduction band offset at increased growth temperatures is observed utilizing the different recombination channels as probes. The optical properties as derived from photoluminescence are correlated with the structural properties obtained by atomic force microscopy. Furthermore, by applying an electric field across the Si/Ge quantum dot structure, a reversed quantum confined Stark effect is demonstrated for the spatially indirect transition. By switching between the two different field directions, unique information on the growth related asymmetric strain profile derived at the through self-assembly of the quantum dots can be gained since corresponding information can not be obtained for type I systems.

    The studies of the InAs/GaAs quantum dots show that external electric and magnetic fields alter the in-plane carrier transport to the dots. The results obtained from the micro-photoluminescence exciton spectra of a single dot demonstrate a redistribution of the excitonic lines when a lateral electric field is applied. This fact exhibits an effective charge reconfiguration of the dot from a purely negative charge state to a neutral state, demonstrating that the number of electrons and holes are controlled by the electric field. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer at low temperatures and low fields. Furthermore, it is demonstrated that the quantum dot photoluminescence signal is considerably increased (up to a factor of 4) depending on the magnitude of the external electric field. The experimental results also show that the internal field is altered by an additional infrared illumination of the sample. An applied magnetic field perpendicular to the quantum dot layer at low temperatures is found to enhance the carrier localization in the wetting layer and accordingly reduce the quantum dot photoluminescence intensity. At higher temperatures (>100K), an enhanced photoluminescence intensity is instead observed due to increased capture, localization, and recombination rate of the carriers in the quantum dots.

    List of papers
    1. Spatially direct and indirect transitions observed for Si/Ge quantum dots
    Open this publication in new window or tab >>Spatially direct and indirect transitions observed for Si/Ge quantum dots
    Show others...
    2003 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 26, p. 4785-4787Article in journal (Refereed) Published
    Abstract [en]

    The optical properties of Ge quantum dots embedded in Si were investigated by means of photoluminescence, with temperature and excitation power density as variable parameters. Two different types of recombination processes related to the Ge quantum dots were observed. A transfer from the spatially indirect to the spatially direct recombination in the type-II band lineup was observed with increasing temperature. A blueshift of the spatially indirect Ge quantum-dot-emission energy with increasing excitation power is ascribed to band bending at the type-II Si/Ge interface for high carrier densities. Comparative studies were performed on uncapped Ge dot structures.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13794 (URN)10.1063/1.1587259 (DOI)
    Available from: 2006-02-27 Created: 2006-02-27 Last updated: 2017-12-13
    2. Reversed quantum-confined Stark effect and an asymmetric band alignment observed for type-II Si∕Ge quantum dots
    Open this publication in new window or tab >>Reversed quantum-confined Stark effect and an asymmetric band alignment observed for type-II Si∕Ge quantum dots
    Show others...
    2005 (English)In: Physical Review B, ISSN 1098-0121, Vol. 71, no 11, p. 113301-Article in journal (Refereed) Published
    Abstract [en]

    We report on the quantum-confined Stark effect for spatially indirect transitions in Stranski-Krastanov grown type-II Si∕Ge quantum dots. A linear blueshift of the spatially indirect transition is observed at increasing electric field in contrast to the commonly observed redshift for type-I transitions. A shift of the emission-peak position and different quenching rates of the photoluminescence for p-i-n and n-i-p diodes at increased electric field and temperature indicate a deeper notch potential for electrons above the dot than below due to a strain-induced asymmetry in the band alignment.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-16331 (URN)10.1103/PhysRevB.71.113301 (DOI)
    Note

    Original Publication: Mats Larsson, Per-Olof Holtz, Anders Elfving, Göran Hansson and Wei-Xin Ni, Reversed quantum-confined Stark effect and an asymmetric band alignment observed for type-II Si∕Ge quantum dots, 2005, Physical Review B, (71), 113301. http://dx.doi.org/10.1103/PhysRevB.71.113301 Copyright: American Physical Society http://www.aps.org/

    Available from: 2009-01-15 Created: 2009-01-15 Last updated: 2012-12-11Bibliographically approved
    3. Band alignment studies in Si/Ge quantum dots based on optical and structural investigations
    Open this publication in new window or tab >>Band alignment studies in Si/Ge quantum dots based on optical and structural investigations
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The present work is a photoluminescence study of Si-embedded Stranski-Krastanov Ge quantum dots. The value of the conduction band offset is a result of the magnitude of the tensile strain in the Si surrounding the compressive strained Ge dot. Due to the increased Si/Ge intermixing and reduced strain in the Si barrier, a reduction of the conduction band offset is observed at increased growth temperatures. The optical properties as derived from photoluminescence spectroscopy are correlated with structural properties obtained as a function of the growth temperature. High growth temperatures result in large Ge dots with low density due to the pronounced surface diffusion and Si/Ge intermixing. As confirmed by photoluminescence, the band gap of the Ge dots increases with increased growth temperature due to the higher degree of Si/Ge intermixing. The band alignment is of type-II in these structures, but the occurrence of both spatially indirect and spatially direct transitions are confirmed in temperature dependent photoluminescence measurements with varied excitation power conditions. An increasing temperature results in a gradual transition from the spatially indirect to the spatially direct recombination in the type-II band lineup, due to higher oscillator strength for the spatially direct transition combined with a higher population factor at higher temperatures.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-86206 (URN)
    Available from: 2012-12-11 Created: 2012-12-11 Last updated: 2012-12-11
    4. Magnetic field effects on optical and transport properties in InAs/GaAs quantum dots
    Open this publication in new window or tab >>Magnetic field effects on optical and transport properties in InAs/GaAs quantum dots
    Show others...
    2006 (English)In: Physical Review B, ISSN 1098-0121, Vol. 74, no 24Article in journal (Refereed) Published
    Abstract [en]

    A photoluminescence study of self-assembled InAs/GaAs quantum dots under the influence of magnetic fields perpendicular and parallel to the dot layer is presented. At low temperatures, the magnetic field perpendicular to the dot layer alters the in-plane transport properties due to localization of carriers in wetting layer (WL) potential fluctuations. Decreased transport in the WL results in a reduced capture into the quantum dots and consequently a weakened dot-related emission. The effect of the magnetic field exhibits a considerable dot density dependence, which confirms the correlation to the in-plane transport properties. An interesting effect is observed at temperatures above approximately 100  K, for which magnetic fields, both perpendicular and parallel to the dot layer, induced an increment of the quantum dot photoluminescence. This effect is ascribed to the magnetic confinement of the exciton wave function, which increases the probability for carrier capture and localization in the dot, but affects also the radiative recombination with a reduced radiative lifetime in the dots under magnetic compression.

    Keywords
    indium compounds, gallium arsenide, III-V semiconductors, semiconductor quantum dots, photoluminescence, magneto-optical effects, self-assembly, localised states, excitons, wave functions, radiative lifetimes, galvanomagnetic effects
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-16330 (URN)10.1103/PhysRevB.74.245312 (DOI)
    Note
    Original Publication: Mats Larsson, Evgenii Moskalenko, Andréas Larsson, Per-Olof Holtz, C. Verdozzi, C.-O. Almbladh, W. V. Schoenfeld and P. M. Petroff, Magnetic field effects on optical and transport properties in InAs/GaAs quantum dots, 2006, Physical Review B, (74), 245312. http://dx.doi.org/10.1103/PhysRevB.74.245312 Copyright: American Physical Society http://www.aps.org/ Available from: 2009-01-15 Created: 2009-01-15 Last updated: 2012-12-11Bibliographically approved
    5. Single InAs/GaAs quantum dot spectroscopy in a lateral electric field
    Open this publication in new window or tab >>Single InAs/GaAs quantum dot spectroscopy in a lateral electric field
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    We report on the comprehensive study of InAs/GaAs single quantum dots subjected to a lateral external electric field by means of micro-photoluminescence (μ-PL) technique. The results obtained on the exciton in the μ-PL spectra of a single dot demonstrate a considerable PL intensity enhancement (up to a factor of 4) of the dot as well as a redistribution of the excitonic lines when an electric field is applied. The latter fact exhibits an effective charge reconfiguration of the dot from a purely negatively charged to a neutral state. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer at low temperature and bias.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-86208 (URN)
    Available from: 2012-12-11 Created: 2012-12-11 Last updated: 2012-12-11
    6. The effect of the external lateral electric field on the luminescence intensity of InAs/GaAs quantum dots
    Open this publication in new window or tab >>The effect of the external lateral electric field on the luminescence intensity of InAs/GaAs quantum dots
    Show others...
    2007 (English)In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 49, no 10, p. 1995-1998Article in journal (Refereed) Published
    Abstract [en]

    We report on low-temperature microphotoluminescence (μ-PL) measurements of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field. It is demonstrated that the QDs’ PL signal could be increased severalfold by altering the external and/or the internal electric field, which could be changed by an additional infrared laser. A model which accounts for a substantially faster lateral transport of the photoexcited carriers achieved in an external electric field is employed to explain the observed effects. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity measured in our experiment—a finding which could be used to tailor the properties of QD-based optoelectronic applications.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-39862 (URN)10.1134/S1063783407100307 (DOI)51544 (Local ID)51544 (Archive number)51544 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
  • 26.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Asymmetric band alignment at Si/Ge quantum dots studied by luminescence from p-i-n and n-i-p structures2005In: ICPS2004,2004, 2005, p. 713-Conference paper (Refereed)
  • 27.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Luminescence study of Si/Ge quantum dots2003In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 16, no 3-4, p. 476-480Article in journal (Refereed)
    Abstract [en]

    We present a photoluminescence (PL) study of Ge quantum dots embedded in Si. Two different types of recombination processes related to the Ge quantum dots are observed in temperature-dependent PL measurements. The Ge dot-related luminescence peak near 0.80 eV is ascribed to the spatially indirect recombination in the type-II band lineup, while a high-energy peak near 0.85 eV has its origin in the spatially direct recombination. A transition from the spatially indirect to the spatially direct recombination is observed as the temperature is increased. The PL dependence of the excitation power shows an upshift of the Ge quantum dot emission energy with increasing excitation power density. The blueshift is ascribed to band bending at the type-II Si/Ge interface at high carrier densities. Comparison is made with results derived from measurements on uncapped samples. For these uncapped samples, no energy shifts due to excitation power or temperatures are observed in contrast to the capped samples.

  • 28.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Photoluminescence study of Si/Ge quantum dots2003In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 532-535, p. 832-836Article in journal (Refereed)
    Abstract [en]

    Ge quantum dots embedded in Si are studied by means of photoluminescence (PL). The temperature dependent PL measurements show two different types of recombination processes related to the quantum dots. We ascribe a peak near 0.80 eV to the spatially indirect recombination in the type-II band lineup where the electron is located in the surrounding Si close to the interface and the hole in the Ge dot. Furthermore, a peak near 0.85 eV is attributed to the spatially direct recombination. We observe a transition from the spatially indirect to the spatially direct recombination as the temperature is increased. The measurements also show an up-shift of the Ge quantum dot emission energy with increasing excitation power density. The blueshift is primarily ascribed to an enhanced confinement of the electron associated with the increased band bending at the type-II Si/Ge interface at high carrier densities. Comparison is made with results, derived from measurements on uncapped samples. For these uncapped samples, no energy shifts due to excitation power or temperatures are observed in contrast to the capped samples. ⌐ 2003 Elsevier Science B.V. All rights reserved.

  • 29.
    Larsson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hansson, Göran
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Spatially direct and indirect transitions observed for Si/Ge quantum dots2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 26, p. 4785-4787Article in journal (Refereed)
    Abstract [en]

    The optical properties of Ge quantum dots embedded in Si were investigated by means of photoluminescence, with temperature and excitation power density as variable parameters. Two different types of recombination processes related to the Ge quantum dots were observed. A transfer from the spatially indirect to the spatially direct recombination in the type-II band lineup was observed with increasing temperature. A blueshift of the spatially indirect Ge quantum-dot-emission energy with increasing excitation power is ascribed to band bending at the type-II Si/Ge interface for high carrier densities. Comparative studies were performed on uncapped Ge dot structures.

  • 30.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Band alignment studies of self-organized Ge/Si quantum dots based on luminescence characterization2005In: The 23rd International Conference on Defects in Semiconductors,2005, 2005Conference paper (Other academic)
  • 31.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Band alignment studies of self-organized Ge/Si quantum dots based on luminescence characterization2005In: The 9th Conference on Optics and Excitons in Confined Systems,2005, 2005Conference paper (Other academic)
  • 32.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Hussain, M.I.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Luminescence Properties of Ge Quantum Dots Produced by MBE at Different Temperatures2004In: Proc. of IEEE/LEOS 1st International Conference on Group IV Photonics,2004, 2004Conference paper (Other academic)
  • 33.
    Larsson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hansson, Göran
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Band alignment studies in Si/Ge quantum dots based on optical and structural investigationsManuscript (preprint) (Other academic)
    Abstract [en]

    The present work is a photoluminescence study of Si-embedded Stranski-Krastanov Ge quantum dots. The value of the conduction band offset is a result of the magnitude of the tensile strain in the Si surrounding the compressive strained Ge dot. Due to the increased Si/Ge intermixing and reduced strain in the Si barrier, a reduction of the conduction band offset is observed at increased growth temperatures. The optical properties as derived from photoluminescence spectroscopy are correlated with structural properties obtained as a function of the growth temperature. High growth temperatures result in large Ge dots with low density due to the pronounced surface diffusion and Si/Ge intermixing. As confirmed by photoluminescence, the band gap of the Ge dots increases with increased growth temperature due to the higher degree of Si/Ge intermixing. The band alignment is of type-II in these structures, but the occurrence of both spatially indirect and spatially direct transitions are confirmed in temperature dependent photoluminescence measurements with varied excitation power conditions. An increasing temperature results in a gradual transition from the spatially indirect to the spatially direct recombination in the type-II band lineup, due to higher oscillator strength for the spatially direct transition combined with a higher population factor at higher temperatures.

  • 34.
    Larsson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Hansson, Göran V.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Growth-temperature-dependent band alignment in Si/Ge quantum dots from photoluminescence spectroscopy2006In: Physical Review B, ISSN 1098-0121, Vol. 73, no 19, p. 195319-1--195319-7Article in journal (Refereed)
    Abstract [en]

    The present work is a photoluminescence study of Si-embedded Stranski-Krastanov Ge quantum dots. The value of the conduction band offset is a result of the magnitude of the tensile strain in the Si surrounding the compressive strained Ge dot. Due to the increased Si/Ge intermixing and reduced strain in the Si barrier, a reduction of the conduction band offset is observed at increased growth temperatures. The optical properties as derived from photoluminescence spectroscopy are correlated with structural properties obtained as a function of the growth temperature. High growth temperatures result in large Ge dots with low density due to the pronounced surface diffusion and Si/Ge intermixing. As confirmed by photoluminescence, the band gap of the Ge dots increases with increased growth temperature due to the higher degree of Si/Ge intermixing. The band alignment is of type II in these structures, but the occurrence of both spatially indirect and spatially direct transitions are confirmed in temperature-dependent photoluminescence measurements with varied excitation power conditions. An increasing temperature results in a gradual transition from the spatially indirect to the spatially direct recombination in the type-II band lineup, due to higher oscillator strength for the spatially direct transition combined with a higher population factor at higher temperatures.

  • 35.
    Larsson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Elfving, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hansson, Göran
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ni, Wei-Xin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Reversed quantum-confined Stark effect and an asymmetric band alignment observed for type-II Si∕Ge quantum dots2005In: Physical Review B, ISSN 1098-0121, Vol. 71, no 11, p. 113301-Article in journal (Refereed)
    Abstract [en]

    We report on the quantum-confined Stark effect for spatially indirect transitions in Stranski-Krastanov grown type-II Si∕Ge quantum dots. A linear blueshift of the spatially indirect transition is observed at increasing electric field in contrast to the commonly observed redshift for type-I transitions. A shift of the emission-peak position and different quenching rates of the photoluminescence for p-i-n and n-i-p diodes at increased electric field and temperature indicate a deeper notch potential for electrons above the dot than below due to a strain-induced asymmetry in the band alignment.

  • 36.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Modified carriers transport and capture into InAs/GaAs quantum dots due to an applied magnetic field2006In: ICPS 28th International Conference on the Physics of Semiconductors,2006, 2006Conference paper (Other academic)
  • 37.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Single dot spectroscopy investigations of carrier transport and capture into InAs/GaAs quantum dots2006In: ICPS 28th International Conference on the Physics of Semiconductors,2006, 2006Conference paper (Other academic)
  • 38.
    Larsson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Tuning the InAs/GaAs quantum dot charge state by pure optical means2006In: ICPS 28th International Conference on the Physics of Semiconductors,2006, 2006Conference paper (Other academic)
  • 39.
    Larsson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Moskalenko, Evgenii
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, Arvid
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Verdozzi, C.
    Solid State Theory, Institute of Physics, Lund University.
    Almbladh, C.-O.
    Solid State Theory, Institute of Physics, Lund University.
    Schoenfeld, W. V.
    Materials Department, University of California, Santa Barbara.
    Petroff, P. M.
    Materials Department, University of California, Santa Barbara.
    Magnetic field effects on optical and transport properties in InAs/GaAs quantum dots2006In: Physical Review B, ISSN 1098-0121, Vol. 74, no 24Article in journal (Refereed)
    Abstract [en]

    A photoluminescence study of self-assembled InAs/GaAs quantum dots under the influence of magnetic fields perpendicular and parallel to the dot layer is presented. At low temperatures, the magnetic field perpendicular to the dot layer alters the in-plane transport properties due to localization of carriers in wetting layer (WL) potential fluctuations. Decreased transport in the WL results in a reduced capture into the quantum dots and consequently a weakened dot-related emission. The effect of the magnetic field exhibits a considerable dot density dependence, which confirms the correlation to the in-plane transport properties. An interesting effect is observed at temperatures above approximately 100  K, for which magnetic fields, both perpendicular and parallel to the dot layer, induced an increment of the quantum dot photoluminescence. This effect is ascribed to the magnetic confinement of the exciton wave function, which increases the probability for carrier capture and localization in the dot, but affects also the radiative recombination with a reduced radiative lifetime in the dots under magnetic compression.

  • 40.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, Arvid
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Schoenfeld, W. V.
    Materials Department, University of California, Santa Barbara.
    Petroff, P. M.
    Materials Department, University of California, Santa Barbara.
    Effective tuning of the charge state of a single InAs/GaAs quantum dot by an external magnetic field2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 7, p. 075306-Article in journal (Refereed)
    Abstract [en]

    A microphotoluminescence study of single InAs/GaAs quantum dots (QDs) in the presence of an applied external magnetic field is presented. Attention is focused on the redistribution between the spectral lines of a single QD observed at increasing magnetic field parallel to the growth direction (Faraday geometry). The redistribution effect is explained by considering the electron drift velocity in the QD plane that affects the probability for capture into the QD. In contrast, no redistribution is observed when applying the magnetic field perpendicular to the growth direction (Voigt geometry).

  • 41.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, Arvid
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Schoenfeld, Winston V
    University of California, USA.
    Petroff, Pierre M
    University of California, USA.
    Comparative Magneto-Photoluminescence Study of Ensembles and of Individual InAs Quantum Dots2009In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, no 1, p. 353-359Article in journal (Refereed)
    Abstract [en]

    We report on magneto-photoluminescence studies of InAs/GaAs quantum dots (QDs) of considerably different densities, from dense ensembles down to individual dots. It is found that a magnetic field applied in Faraday geometry decreases the photoluminescence (PL) intensity of OD ensembles, which is not accompanied by the corresponding increase of PL signal of the wetting layer on which ON are grown. The model suggested to explain these data assumes considerably different strengths of suppression of electron and hole fluxes by a magnetic field. This idea has been successfully checked in experiments on individual ON, where the PL spectra allow to directly monitor the charge state of a OD and, hence, to conclude about relative magnitudes of electron and hole fluxes toward the QD. Comparative studies of different individual QDs have revealed that the internal electric field in the sample (which was altered in the experiments in a controllable way) together with an external magnetic field will determine the charge state and emission intensity of the QDs.

  • 42.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Schoenfeld, W. V.
    Materials Department, University of California, Santa Barbara.
    Petroff, P. M.
    Materials Department, University of California, Santa Barbara.
    Carrier transport in self-organized InAs/GaAs quantum-dot structures studied by single-dot spectroscopy2006In: Physical Review B, ISSN 1098-0121 , Vol. 73, no 15Article in journal (Refereed)
    Abstract [en]

    A microphotoluminescence study of single InAs/GaAs quantum dots subjected to a lateral external electric field gives insight into carrier transport and capture processes into Stranski-Krastanov-grown quantum dots. The results obtained on the excitons in a single dot demonstrate a considerable luminescence intensity enhancement of the dot as well as a charge redistribution when an electric field is applied. The charge reconfiguration is evidenced by the transition from a predominantly negatively charged to a neutral charge state of the exciton. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer.

  • 43.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Verdozzi, C.
    Solid State Theory, Institute of Physics, Lund University, Lund, Sweden.
    Almbladh, C.-O.
    Solid State Theory, Institute of Physics, Lund University, Lund, Sweden.
    Schoenfeld, W. V.
    Materials Department, University of California, Santa Barbara, California.
    Petroff, P. M.
    Materials Department, University of California, Santa Barbara, California.
    Single InAs/GaAs quantum dot spectroscopy in a lateral electric fieldManuscript (preprint) (Other academic)
    Abstract [en]

    We report on the comprehensive study of InAs/GaAs single quantum dots subjected to a lateral external electric field by means of micro-photoluminescence (μ-PL) technique. The results obtained on the exciton in the μ-PL spectra of a single dot demonstrate a considerable PL intensity enhancement (up to a factor of 4) of the dot as well as a redistribution of the excitonic lines when an electric field is applied. The latter fact exhibits an effective charge reconfiguration of the dot from a purely negatively charged to a neutral state. The model proposed to explain the charge redistribution is based on an effective hole localization at the potential fluctuations of the wetting layer at low temperature and bias.

  • 44.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Enhancement of the luminescence intensity of InAs/GaAs quantum dots induced by an external electric field2007In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 7, no 1, p. 188-193Article in journal (Refereed)
    Abstract [en]

    InAs/GaAs quantum dots have been subjected to a lateral external electric field in low-temperature microphotoluminescence measurements. It is demonstrated that the dot PL signal could be increased several times depending on the magnitude of the external field and the strength of the internal (built-in) electric field, which could be altered by an additional infrared illumination of the sample. The observed effects are explained by a model that accounts for the essentially faster lateral transport of the photoexcited carriers achieved in an electric field. © 2007 American Chemical Society.

  • 45.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Larsson, Mats
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Karlsson, Fredrik
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Monemar, Bo
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Schoenfeld, W.V.
    Materials Department, University of California, Santa Barbara, United States.
    Petroff, P.M.
    Materials Department, University of California, Santa Barbara, United States.
    The effect of the external lateral electric field on the luminescence intensity of InAs/GaAs quantum dots2007In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 49, no 10, p. 1995-1998Article in journal (Refereed)
    Abstract [en]

    We report on low-temperature microphotoluminescence (μ-PL) measurements of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field. It is demonstrated that the QDs’ PL signal could be increased severalfold by altering the external and/or the internal electric field, which could be changed by an additional infrared laser. A model which accounts for a substantially faster lateral transport of the photoexcited carriers achieved in an external electric field is employed to explain the observed effects. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity measured in our experiment—a finding which could be used to tailor the properties of QD-based optoelectronic applications.

  • 46.
    Moskalenko, Evgeny
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Larsson, Arvid
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, P.M.
    Effective tuning of the charge state of a single InAs/GaAs quantum dot by means of external fields2008In: One Day Quantum Dot Meeting,2008, 2008Conference paper (Other academic)
  • 47.
    Ni, Wei-Xin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Elfving, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hansson, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Si-based Photonic Transistor Devices for Integrated Optoelectronics2003In: The 3rd International Conference on SiGe Epitaxy and Heterostructures,2003, 2003, p. 231-Conference paper (Refereed)
    Abstract [en]

      

  • 48. Shubina, Tatiana
    et al.
    Plotnikov, D.S.
    Vasson, A.
    Leymarie, J.
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lu, H.
    Schaff, W.J.
    Kop¿ev, P.S.
    Surface-plasmon resonances in indium nitride with metal-enriched nano-particles2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 288, no 2, p. 230-235Article in journal (Refereed)
    Abstract [en]

    Plasmonic resonances in In-enriched nano-particles, spontaneously formed during growth, can dramatically modify optical properties of InN. Experimental support for this is provided from detailed studies of absorption and infrared emission in InN. In particular, thermally detected optical absorption and photoluminescence excitation spectroscopy reveal a peak below the region of strong absorption in InN. A higher-energy part of the infrared emission having a noticeable p-polarization is markedly enhanced with excitation along the surface. These peculiarities are discussed in terms of the Mie resonances, arising in metallic spheroids with different aspect ratio, and their coupling with recombining states, whose strength depends on energy separation between the states and the resonances. © 2005 Elsevier B.V. All rights reserved.

  • 49. Zhuravlev, K S
    et al.
    Mansurov, V G
    Yu, A
    Nikitin, A
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Mobile and immobile photoluminescence bands from single hexagonal GaN quantum dots embedded in an AlN matrix2008In: ICPS 29th International Conference on the Physics of Semiconductors,2008, 2008Conference paper (Refereed)
  • 50. Zhuravlev, KS
    et al.
    Mansurov, VG
    YU, A
    Nikitin, A
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Power dependence of photoluminescence from single hexagonal GaN quantum dots formed in an AlN matrix2007In: NANO-2007 workshop,2007, 2007Conference paper (Refereed)
12 1 - 50 of 51
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