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2007 Fiscal Year Final Research Report Summary

Self-assembled quantum dots based on use of dilute nitride semiconductors

Research Project

Project/Area Number 17360135
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Electronic materials/Electric materials
Research InstitutionUniversity of Tsukuba

Principal Investigator

OKADA Yoshitaka  University of Tsukuba, Graduate School of Pure and Applied Sciences, Associate professor (40224034)

Project Period (FY) 2005 – 2007
KeywordsQuantum dots / Self-assembled growth / Dilute nitride semiconductors / Strain-control / Molecular beam enitaxy(MBE) / High efficiencv solar cells
Research Abstract

First, self-assembled Ga_xIn_<1-x> N_yAs_<l-y> quantum dot structures fabricated on GaAs (001) substrates have been studied with atomic-Hydrogen assisted molecular beam epitaxy and a radio frequency nitrogen plasma source. The GaInNAs quantum dots are promising for extending emission wavelengths from 1. 3 to 1.55 um and beyond. We succeeded in achieving high densities on the order of 1. 1x10^<11> cm^<-2> for Ga_<0.53> In_<0.47> No_<0.02> As_<0.98> quantum dots on GaAs (001). Further, we studied the effect of H_2 flux on both the growth dynamics and the optical properties, and found that an optimum H_2 flux rate for Ga_<0.53> In_<0.47> No_<0.02> As_<0.98> quantum dot growth in our system is at around 0.6sccm. These results are attributed to originate from improvement of crystal quality of GaInNAs quantum dots by irradiation of atomic H.
Next, we investigated a growth technique to fabricate multiple-stacked InAs self-assembled quantum dots on GaAs (001) substrates. The stacking of dots is achieved by strain compensation technique, in which GaNAs is used as a spacer layer to bury a quantum dot layer. No dislocations are observed even after 20 layers of stacking, and the area density of quantum dots amounted to the order of 10^<12> cm^<-2>. From photoluminescence measurements, a single emission peak from quantum dots is clearly observed at around 1200 nm at room temperature. Further, the emission peak energy straightforwardly shifts to longer wavelengths with increasing N composition in GaNAs spacer layer due to the lowering the quantum confinement energy or barrier height.

  • Research Products

    (6 results)

All 2007 2006

All Journal Article (4 results) Presentation (1 results) Book (1 results)

  • [Journal Article] MBE growth of InAs self-assembled quantum dots embedded in GaNAs strain-compensating layers2007

    • Author(s)
      T. Hashimoto, R. Oshima, H. Shigekawa, and Y. Okada
    • Journal Title

      J. Crystal Growth 301

      Pages: 821-824

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Next-generation solar cells with quantum nanostrucrures2007

    • Author(s)
      Y. Okada and R. Oshima
    • Journal Title

      Oyo Butsuri 76

      Pages: 50-53

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Multiple stacking of self-assembled quantum dots embedded by GaNAs strain compensating layers2006

    • Author(s)
      R. Oshima, T. hashimoto, H. Shigekawa, and Y. Okada
    • Journal Title

      J. Appl. Phys 100

      Pages: 083110(1)-(4)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Long wavelength InAs self- assembled quantum dots embedded in GaNAs strain-compensating layers2006

    • Author(s)
      R. Oshima, T. Hashimoto, H. Shigekawa, and Y. Okada
    • Journal Title

      Physica E 32

      Pages: 77-80

    • Description
      「研究成果報告書概要(欧文)」より
  • [Presentation] Multiple stacking of self-assembled quantum dots embedded by GaNAs strain compensating layers2006

    • Author(s)
      R. Oshima, T. Hashimoto, H. Shigekawa, and Y. Okada
    • Organizer
      28th International Conference on Physics of Semiconductors
    • Place of Presentation
      Vienna(Austria)
    • Year and Date
      2006-07-26
    • Description
      「研究成果報告書概要(欧文)」より
  • [Book] 量子ナノ構造を導入した次世代太陽電池2007

    • Author(s)
      岡田至崇・大島隆治
    • Total Pages
      4
    • Publisher
      応用物理学会
    • Description
      「研究成果報告書概要(和文)」より

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Published: 2010-02-04  

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