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2006 Fiscal Year Final Research Report Summary

Low temperature near-field optical mapping and control of electron wavefunctions confined in nanostructures

Research Project

Project/Area Number 16310075
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Nanostructural science
Research InstitutionKeio University

Principal Investigator

SAIKI Toshiharu  Keio University, Faculty of Science and Technology, Associate Professor, 理工学部, 助教授 (70261196)

Co-Investigator(Kenkyū-buntansha) NOMURA Shintaro  University of Tsukuba, Graduate School of Pure and probed Sciences, Associate Professor, 大学院数理物質科学研究科, 助教授 (90271527)
Project Period (FY) 2004 – 2006
KeywordsWavefunction / Near-field optical microscope / Quantum dot / Nitride semiconductor / Local density of states
Research Abstract

We have established a near-field scanning optical microscope (NSOM) system with a high spatial resolution under a magnetic field up to 5T at low temperature. The spatial resolution as high as 30-50 nm enabled us to visualize exciton wave functions confined in single quantum dots.
In GaAs/AlGaAs interface quantum dots, the wavefunctions of ground-state exciton, excited-state exciton, and biexciton states are clearly mapped out. A numerical calculation reproduced the experimental results well in their quantitative nature. We also applied this technique to visualize the local density of states of excitons confined in an electric-field induced quantum dot system. We observed that electrons confined in lower energy states localized more strongly.
Dilute nitride alloy systems such as GaNAs and GaInNAs were investigated to clarify nonuniform distribution of N atoms through the spatially resolved spectroscopy of localized and delocalized electron states. The depths and spatial profiles of exciton confinement potential were visualized through the measurement of power-dependent PL spectra and high-resolution PL images. For two GaInNAs quantum wells with different N contents, we observed strongly localized excitons confined in N clusters and rather delocalized excitons, which indicate the onset of alloy formation.
From magneto-PL spectroscopy of a single QD, a diamagnetic shift of the exciton emission was observed. Referring to the theoretical value we estimate the size of the QD from a diamagnetic coefficient, which is determined by the Bohr radius of excitons confined in QDs. The result was in good agreement with that obtained by the real-space NSOM mapping.

  • Research Products

    (9 results)

All 2007 2006 2005 2004

All Journal Article (8 results) Book (1 results)

  • [Journal Article] Two-exciton state in GaSb/GaAs type II quantum dots studied using near-field photoluminescence spectroscopy2007

    • Author(s)
      K.Matsuda, S.V.Nair, H.E.Ruda, Y.Sugimoto, T.Saiki, K.Yamaguchi
    • Journal Title

      Appl. Phys. Lett. 90

      Pages: 13101

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] FDTD modeling of a polarization near-field scanning optical microscope2006

    • Author(s)
      K.Sawada, M.Sakai, Y.Kohashi, T.Saiki, H.Nakamura
    • Journal Title

      J. Plasma Phys. 72

      Pages: 1019-1023

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Local density of states mapping of a field-induced quantum dot by near-field photoluminescence microscopy2005

    • Author(s)
      K.Matsuda, T.Saiki, S.Nomura, Y.Aoyagi
    • Journal Title

      Appl. Phys. Lett. 87

      Pages: 43112

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Nano-optical probing of exciton wave-functions confined in a GaAs quantum dot2004

    • Author(s)
      T.Saiki, K.Matsuda, S.Nomura, M.Mihara, Y.Aoyagi, S.Nair, T.Takagahara
    • Journal Title

      J. Electron Microscopy 53

      Pages: 193-201

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Near-field photoluminescence imaging spectroscopy of ann-type modulation-doped quantum well with a lateral periodic potential2004

    • Author(s)
      K.Matsuda, T.Saiki, S.Nomura, Y.Aoyagi
    • Journal Title

      Nanotechnology 15

      Pages: 345-348

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Direct optical observation of compositional fluctuation in GaAs_<1-x>N_x by near-field photoluminescence spectroscopy and microscopy with high spatial resolution2004

    • Author(s)
      K.Matsuda, T.Saiki, T.Yamada, T.Ishizuka
    • Journal Title

      Appl. Phys. Lett. 85

      Pages: 3077-3079

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Near-field photoluminescence imaging spectroscopy of an n-type modulation-doped quantum well with a lateral periodic potential2004

    • Author(s)
      K.Matsuda, T.Saiki, S.Nomura, Y.Aoyagi
    • Journal Title

      Nanotechnology 15

      Pages: S345-S348

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Direct optical observation of compositional fluctuation in GaAs_<1-x>N_x, by near-field photoluminescence spectroscopy and microscopy with high spatial resolution2004

    • Author(s)
      K.Matsuda, T.Saiki, T.Yamada, T.Ishizuka
    • Journal Title

      Appl. Phys. Lett. 85

      Pages: 3077-3079

    • Description
      「研究成果報告書概要(欧文)」より
  • [Book] Roadmap of Scanning Probe Microscope2006

    • Author(s)
      T.Saiki
    • Total Pages
      201
    • Publisher
      Springer-Verlag
    • Description
      「研究成果報告書概要(和文)」より

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Published: 2008-05-27  

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