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  • 1.
    Amloy, Supaluck
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, Evgenii
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Eriksson, M
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Karlsson, K Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    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
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 6Article in journal (Refereed)
    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.

  • 2. Donchev, V.
    et al.
    Karlsson, Fredrik
    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 .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, J.M.
    Garcia, J.M.
    Petroff, M.
    Temperature Study of the Photoluminescence of a Single InAs/GaAs Quantum Dot2004In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 3, p. 608-Article in journal (Refereed)
    Abstract [en]

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

  • 3. Donchev, V.
    et al.
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, K.F.
    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.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Garcia, J.M.
    Institute de Microelectronica de Madrid, CNM-CSIC Isaak Newton 8, PTM 28760, Tres Cantos, Madrid, Spain.
    Petroff, P.M.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Enhancement of the photoluminescence intensity of a single InAs/GaAs quantum dot by separate generation of electrons and holes2006In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 48, no 10, p. 1993-1999Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that the microphotoluminescence (µPL) spectrum of a single InAs/GaAs self-assembled quantum dot (QD) undergoes considerable changes when the primary laser excitation is complemented with an additional infrared laser. The primary laser, tuned slightly below the GaAs band gap, provides electron-hole pairs in the wetting layer (WL), as well as excess free electrons from ionized shallow acceptors in the GaAs barriers. An additional IR laser with a fixed energy well below the QD ground state transition generates excess free holes from deep levels in GaAs. The excess electron and hole will experience diffusion separately, due to the time separation between the two events of their generation, to eventually become captured into the QD. Although the generation rates of excess carries are much lower than that of the electron-hole pair generation in the WL, they considerably influence the QD emission at low temperatures. The integrated PL intensity increases by several times as compared to single-laser excitation, and the QD exciton spectrum is redistributed in favor of a more neutral charge configuration. The dependence of the observed phenomenon on the powers of the two lasers and the temperature has been studied and is consistent with the model proposed. The concept of dual excitation could be successfully applied to different low-dimensional semiconductor structures in order to manipulate their charge state and emission intensity. © Nauka/Interperiodica 2006.

  • 4.
    Holtz, Per-Olof
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hsu, Chih-Wei
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Larsson, L A
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Karlsson, K Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Dufåker, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lundskog, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, Evgenii
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    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 dots2012In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 407, no 10, p. 1472-1475Article in journal (Refereed)
    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.

  • 5.
    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)
  • 6.
    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.

  • 7.
    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]

      

  • 8.
    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)
  • 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.
    Enhanced Luminescence from Self-Assembled Quantum Dots2006In: 14th Interenational School on Condensed Matter Physics,2006, 2006Conference paper (Other academic)
  • 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.
    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]

       

  • 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.
    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]

       

  • 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.
    Optical Properties of Self-Assembled Quantum Dots2006In: Scientific INTAS-SB RAS Workshop,2006, 2006Conference paper (Other academic)
  • 13.
    Hsu, Chih-Wei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, Evgenii
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lundskog, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Karlsson, Fredrik K.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    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.
    The charged exciton in an InGaN quantum dot on a GaN pyramid2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 1Article in journal (Refereed)
    Abstract [en]

    The emission of a charged exciton in an InGaN quantum dot (QD) on top of a GaN pyramid is identified experimentally. The intensity of the charged exciton exhibits the expected competition with that of the single exciton, as observed in temperature-dependent micro-photoluminescence measurements, performed with different excitation energies. The non-zero charge state of this complex is further supported by time resolved micro-photoluminescence measurements, which excludes neutral alternatives of biexciton. The potential fluctuations in the vicinity of the QD that localizes the charge carriers are proposed to be responsible for the unequal supply of electrons and holes into the QD.

  • 14.
    Karlsson, Fredrik
    et al.
    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 .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Effective tuning of the charge-state of single In(Ga)As/GaAs quantum dots by below barrier band gap excitation2003In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 532-535, p. 843-847Article in journal (Refereed)
    Abstract [en]

    The existence of a well-defined threshold energy, crucial for the charging of quantum dots (QDs), positioned between the barrier band gap and the wetting layer ground state is demonstrated. Optical excitation with energies above this threshold populates the QDs with extra electrons. The origin of the threshold is discussed in terms of acceptors in the GaAs barrier. ⌐ 2003 Elsevier Science B.V. All rights reserved.

  • 15.
    Karlsson, Fredrik
    et al.
    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 .
    Moskalenko, Evgenii
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Quantum dots as a sensitive tool to monitor charge2002In: 14th Indium Phosphide and Related Materials Conference IPRM 2002,2002, 2002, p. 75-Conference paper (Refereed)
  • 16.
    Karlsson, Fredrik
    et al.
    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 .
    Moskalenko, Evgeny
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Step-like dependence of the exciton charge-state on the excitation energy in single In(Ga)As/GaAs quantum dots2003In: ICPS,2003, 2003Conference paper (Refereed)
  • 17.
    Karlsson, Fredrik
    et al.
    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 .
    Moskalenko, Evgeny
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    The quantum dot as a sensitive probe for impurities in its vicinity2003In: 11th International Conference on Modulated Semiconductor Structures MSS-11,2003, 2003Conference paper (Other academic)
  • 18.
    Karlsson, Fredrik
    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 .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Garcia, J.M.
    Schoenfeld, W.V.
    Petroff, P.M.
    The influence of carrier diffusion on the formation of charged excitons in InAs/GaAs quantum dots2002In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 13, no 2-4, p. 101-104Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that the photoluminescence spectra of single self-assembled quantum dots are very sensitive to the excitation energy and crystal temperature. A qualitative explanation is given in terms of the effective diffusivity of the photogenerated carriers, determined by the experimental conditions, which influence the capture probability and hence also the charge state of the quantum dots (QDs). This is proposed as an effective tool to populate quantum dots with extra electrons in order to study phenomena involving charged excitons. ⌐ 2002 Elsevier Science B.V. All rights reserved.

  • 19.
    Karlsson, Fredrik
    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 .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Optical charging of self-assembled InAs/GaAs quantum dots2002In: Physica scripta. T, ISSN 0281-1847, Vol. 101, p. 140-142Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that the photoluminescence spectra of single self-assembled quantum dots are very sensitive to the experimental conditions, such as excitation energy and crystal temperature. A qualitative explanation is given in terms of the effective diffusion of the photogenerated carriers, determined by the experimental conditions, which influence the capture probability and hence also the charge state of the quantum dots. This is proposed as an effective tool to populate single quantum dots with extra electrons, by purely optical means, in order to study phenomena involving charged excitons.

  • 20.
    Karlsson, Fredrik
    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 .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Temperature influence on optical charging of self-assembled InAs/GaAs semiconductor quantum dots2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 19, p. 2952-2954Article in journal (Refereed)
    Abstract [en]

    It is demonstrated that the photoluminescence spectra of single self-assembled InAs/GaAs quantum dots are very sensitive to excitation energy and crystal temperature. This is qualitatively explained in terms of the effective diffusivity of photogenerated particles, which affects the capture probability of the quantum dot. As a consequence, this opens the possibility of controlling the average number of excess electrons in the quantum dot by optical means. This technique may be used as a simple tool to create and study charged exciton complexes without any specially fabricated samples. ⌐ 2001 American Institute of Physics.

  • 21.
    Karlsson, Fredrik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Moskalenko, Evgeny
    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, Semiconductor Materials.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Carrier diffusion in the barrier enabling formation of charged excitons in InAs/GaAs quantum dots2001In: XXX International School on the Physics of Semiconducting Compounds,2001, Polish Academy of Sciences, Institute of Physics , 2001, Vol. 100, p. 387-395Conference paper (Refereed)
    Abstract [en]

    It is demonstrated that the photoluminescence spectra of single self-assembled quantum dots are very sensitive to the experimental conditions, such as excitation energy and crystal temperature. A qualitative explanation is given in terms of the effective diffusion of the photogenerated carriers, determined by the experimental conditions, which influence the capture probability and hence also the charge state of the quantum dots. This is proposed as a new tool to populate quantum dots with extra electrons in order to study phenomena involving charged excitons.

  • 22.
    Larsson, Arvid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Moskalenko, Evgenii
    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.
    Manipulating the Spin Polarization of Excitons in a Single Quantum Dot by Optical Means2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 7, p. 071906-Article in journal (Refereed)
    Abstract [en]

    Circular polarization studies of photoluminescence from the neutral (X0) and the positively charged (X+) exciton are reported for individual InAs/GaAs quantum dots (QDs). High polarization degrees, 60 % for X0 and 73 % for X+, were recorded without any external magnetic field applied. These studies show that that the QD polarization and population dynamics are controllable either by varying the photo-excitation intensity, or by using a second IR laser excitation.

  • 23.
    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.

  • 24.
    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]

      

  • 25.
    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)
  • 26.
    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)
  • 27.
    Larsson, L. A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Moskalenko, E. S.
    A. F. Ioffe Physical‐Technical Institute, 194021, Polytechnicheskaya 26, St. Petersburg, Russia .
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Quantum Dot Charging By Means Of Temperature And Magnetic Field2011Conference paper (Other academic)
    Abstract [en]

    A micro‐photoluminescence study of individual InAs/GaAs quantum dots is presented. It is demonstrated that by varying the strength of an applied magnetic field and/or the temperature, the charge state of a quantum dot can be tuned. The charge tuning mechanism is shown to be due to the modification of the electron and hole transport in the wetting layer plane prior to their capture into the quantum dot.

  • 28.
    Larsson, L. A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Moskalenko, E. S.
    A. F. Ioffe Physical‐Technical Institute, 194021, Polytechnicheskaya 26, St. Petersburg, Russia .
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Spin Polarizing Neutral Excitons In Quantum Dots2011Conference paper (Other academic)
    Abstract [en]

    A high degree of spin polarization for the neutral exciton in individual InAs quantum dots, without any external magnetic field applied, is demonstrated. The polarization mechanism is shown to be due to the difference in capture time into the QD for the electrons and holes after photo excitation in the wetting layer. This leads to optical pumping of the QD nuclei by spin polarized electrons and hence suppression of the anisotropic electron—hole exchange interaction.

  • 29.
    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)
  • 30.
    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)
  • 31.
    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)
  • 32.
    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.

  • 33.
    Moskalenko, Evgeni
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Karlsson, K.F.
    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 .
    Donchev, V.
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Formation of the negatively charged exciton complexes in InAs quantum dots2006In: Seminar Excitons and Exciton Condensates in Confined Semiconductor Systems,2006, 2006, p. 24-Conference paper (Refereed)
  • 34.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Donchev, V.
    Karlsson, Fredrik
    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.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, M.
    Effect of an additional infrared excitation on the luminescence efficiency of a single InAs/GaAs quantum dot2003In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 15, p. 1553171-15531714Article in journal (Refereed)
    Abstract [en]

    Microphotoluminescence (PL) spectra of a single InAs/GaAs self-assembled quantum dot (QD) are studied under the main excitation of electron-hole pairs in the wetting layer (WL) and an additional infrared (IR) laser illumination. It is demonstrated that the IR laser with fixed photon energy well below the QD ground state induces striking changes in the spectra for a range of excitation energies and powers of the two lasers. For the main excitation above a threshold energy, defined as the onset of transitions between shallow acceptors and the conduction band in GaAs, the addition of the IR laser will induce a considerable increase in the QD emission intensity. This is explained in terms of additional generation of extra electrons and holes into the QD by the two lasers. For excitation below the threshold energy, the carrier capture efficiency from the WL into the QD is suggested to be essentially determined by the internal electric-field-driven carrier transport in the plane of the WL. The extra holes, generated in the GaAs by the IR laser, are supposed to effectively screen the built-in field, which results in a considerable reduction of the carrier collection efficiency into the QD and, consequently, a decrease of the QD PL intensity. A model is presented which allows estimating the magnitude of the built-in field as well as the dependence of the observed increase of the QD PL intensity on the powers of the two lasers. The use of an additional IR laser is considered to be helpful to effectively manipulate the emission efficiency of the quantum dot, which could be used in practice in quantum-dot-based optical switches.

  • 35.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Donchev, V.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Petroff, M.
    The quenching effect of the light emission from individual InAs quantum dots initiated by an additional infra-red laser2004In: The Repino 2004 Conference,2004, 2004Conference paper (Other academic)
  • 36.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Donchev, V.
    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.
    The effect of an additional infrared laser on the carrier collection efficiency of InAs quantum dots2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 24, p. 4896-4898Article in journal (Refereed)
    Abstract [en]

    The impact of single and multi-quantum dots (QD) on the exposure by a low-energy laser was investigated using micro-photoluminescence. The presence of the low-energy laser effectively quenched the single QD luminescence, at low temperatures. An induced screening of a built-in electric field that played an important role as a carrier capture mechanism led to this effect. When the capture efficieny was increased by elevated crystal temperature, the influence of the low-energy laser decreased.

  • 37.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Karlsson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Donchev, V.T.
    Faculty of Physics, Sofia University, 5, Boulevard James Bourchier, 1164-Sofia, Bulgaria.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Monemar, Bo
    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, CA 93106.
    Petroff, P.M.
    Materials Department, University of California, Santa Barbara, CA 93106.
    Effects of separate carrier generation on the emission properties of InAs/GaAs quantum dots2005In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 5, no 11, p. 2117-2122Article in journal (Refereed)
    Abstract [en]

    Individual quantum dots have been studied by means of microphotoluminescence with dual-laser excitation. The additional infrared laser influences the dot charge configuration and increases the dot luminescence intensity. This is explained in terms of separate generation of excess electrons and holes into the dot from the two lasers. With increasing dot density and/or sample temperature, the increase of the luminescence intensity vanishes progressively, while the possibility to control the dot charge remains. © 2005 American Chemical Society.

  • 38.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    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.
    Garcia, J.M.
    Petroff, P.M.
    Acceptor-induced threshold energy for the optical charging of InAs single quantum dots2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 19, p. 1953321-19533211Article in journal (Refereed)
    Abstract [en]

    We study the photoluminescence of single InAs/GaAs self-assembled quantum dots for a range of excitation powers, excitation energies and sample temperatures 4 K30 K), this effect vanishes due to the essential decrease of the steady-state free electron concentration in the GaAs barrier as a result of thermally excited free holes appearing in the GaAs barrier valence band which provides an effective recombination channel for the free electrons. These experimental observations could be used as an effective tool to create and study charged excitons in quantum dots.

  • 39.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    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.
    Garcia, J.M.
    Petroff, P.M.
    Formation of the charged exciton complexes in self-assembled InAs single quantum dots2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 92, no 11, p. 6787-6793Article in journal (Refereed)
    Abstract [en]

    The low-temperature photoluminescence (PL) of the self-assembled InAs single quantum dots (QD) was studied using micro-PL setup. It was demonstrated that two emission lines down shifted in energy with respect to the ground state exciton PL line appeared in the PL spectrum. The PL intensity of these lines showed a periodic behavior with the excitation energy.

  • 40.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, Fredrik
    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.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Schoenfeld, W.V.
    Garcia, J.M.
    Petroff, P.M.
    Influence of excitation energy on charged exciton formation in self-assembled InAs single quantum dots2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, p. 085302-Article in journal (Refereed)
  • 41.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    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.
    Garcia, J.M.
    Petroff, P.M.
    The formation of the charged exciton complexes in self-assembled InAs single quantum dots2001In: The 9th International Symposium on Nanostructures,2001, 2001, p. 558-Conference paper (Refereed)
  • 42.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    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 .
    Schoenfeld, W.V.
    Petroff, P.M.
    The role of an external electric field for the carrier transport and capture into InAs/GaAs quantum dots2005In: The 23rd International Conference on Defects in Semiconductors,2005, 2005Conference paper (Other academic)
  • 43.
    Moskalenko, Evgenii
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, K.Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Donchev, V.
    Faculty of Physics, Sofia University, Sofia, 1164, Bulgaria.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Schoenfeld, W.V.
    Department of Materials, University of California, Santa Barbara, CA 93106, United States.
    Petroff, P.M.
    Department of Materials, University of California, Santa Barbara, CA 93106, United States.
    Effect of an electric field on the carrier collection efficiency of InAs quantum dots2005In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 47, no 11, p. 2154-2161Article in journal (Refereed)
    Abstract [en]

    Individual and multiquantum dots of InAs are studied by means of microphotoluminescence in the case where, in addition to the principal laser exciting photoluminescence, second infrared laser is used. It is demonstrated that the absorption of the infrared photons effectively creates free holes in the sample, which leads to both a change in the charge state of a quantum dot and to a considerable reduction of their photoluminescence signal. The latter effect is explained in terms of effective screening of the internal electric field, facilitating carrier transport along the plane of a wetting layer, by the surplus holes from the infrared laser. It is shown that the effect of quenching of quantum dot photoluminescence gradually disappears at increased sample temperature (T) and/or dot density. This fact is due to the essentially increased value of quantum dot collection efficiency, which could be achieved at elevated sample temperatures for individual quantum dots or even at low T for the case of multiquantum dots. It is suggested that the observed phenomena can be widely used in practice to effectively manipulate the collection efficiency and the charge state of quantum-dot-based optical devices. © 2005 Pleiades Publishing, Inc.

  • 44.
    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.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Spin polarization of neutral excitons in quantum dots: the role of the carrier collection area2010In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, NANOTECHNOLOGY, Vol. 21, no 34Article in journal (Refereed)
    Abstract [en]

    A high degree (approximate to 55%) of circular polarization has been observed for the neutral exciton in InAs/GaAs quantum dots (QDs). The possibility to record non- zero polarization of the neutral exciton is explained in terms of different capture times of the light electron compared with the heavier holes into the QDs from the wetting layer. This interpretation is supported by the progressive reduction of the polarization degree with increasing QD density, and also with increasing temperature.

  • 45.
    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.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Spin polarization of the neutral exciton in a single InAs quantum dot at zero magnetic field2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 80, no 19, p. 193413-Article in journal (Refereed)
    Abstract [en]

    A high degree of spin polarization for the neutral exciton in individual quantum dots, at zero external magnetic field, is monitored. While a high polarization degree is commonly observed for the charged exciton, a negligible polarization has been predicted for the neutral exciton. The exceptionally high polarization (andgt;60%) observed here is explained in terms of a dynamical nuclear polarization field, stabilizing the electron spin. Such polarization of the quantum dot nuclei, in case of the neutral exciton, is possible due to unequal capture time of electrons and holes.

  • 46.
    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).

  • 47.
    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.

  • 48.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, L A
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Spin polarization of the neutral exciton in a single quantum dot2011In: SUPERLATTICES AND MICROSTRUCTURES, ISSN 0749-6036, Vol. 49, no 3, p. 294-299Article in journal (Refereed)
    Abstract [en]

    While efficient nuclear polarization has earlier been reported for the charged exciton in InAs/GaAs quantum dots at zero external magnetic field, we report here on a surprisingly high degree of circular polarization, up to approximate to 60%, for the neutral exciton emission in individual InAs/GaAs dots. This high degree of polarization is explained in terms of the appearance of an effective nuclear magnetic field which stabilizes the electron spin. The nuclear polarization is manifested in experiments as a detectable Overhauser shift. In turn, the nuclei located inside the dot are exposed to an effective electron magnetic field, the Knight field. This nuclear polarization is understood as being due to the dynamical nuclear polarization by an electron localized in the QD. The high degree of polarization for the neutral exciton is also suggested to be due to separate in-time capture of electrons and holes into the QD.

  • 49.
    Moskalenko, Evgenii
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Larsson, L.A.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Circularly polarized emission from ensembles of InAs/GaAs quantum dots2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 1, p. 013510-Article in journal (Refereed)
    Abstract [en]

    We present a low-temperature micro-photoluminescence (mu-PL) study of ensembles of InAs/GaAs quantum dots (QDs) with respect to its circular polarization (rho(c)) for a manifold of experimental conditions such as single or dual laser excitation, different excitation energies (h upsilon(ex)), varying excitation powers (P(ex)) of both lasers, and with or without an external magnetic field (B(ext)). It is demonstrated that an essential rho(c) (less than= 40%) could be recorded depending on P(ex), even at B(ext) = 0 for h upsilon(ex) exceeding the PL energy of the wetting layer (E(WL)), while rho(c) remains negligible for h upsilon(ex) less than E(WL). To explain the data obtained, a model is developed according to which a nuclear magnetic field (B(N)) is created in the QDs by spin-polarized electrons. The B(N) plays a crucial role in the preservation of the electron spin, which otherwise effectively relaxes due to the presence of the anisotropic electron-hole exchange interaction (omega(ex)). The application of an additional infra-red laser gives rise to a population of excess holes in the QDs, thus producing positively charged excitons. In this case, omega(ex) = 0 and accordingly, rho(c) approximate to 40% at B(ext) = 0 is recorded, even for excitation with h upsilon(ex) less than E(WL).

  • 50.
    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.

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