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1998 Fiscal Year Final Research Report Summary

Study of electronic states in 10nm-scale semiconductor quantum dots and exploration of their memory functions

Research Project

Project/Area Number 09450136
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 電子デバイス・機器工学
Research InstitutionThe University of Tokyo

Principal Investigator

SAKAKI Hiroyuki  The University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (90013226)

Co-Investigator(Kenkyū-buntansha) NODA Takeshi  The University of Tokyo, Research Center for Advanced Science and Technology, Re, 先端技術研究センター, 助手 (90251462)
TAKAHASHI Takuji  The University of Tokyo, Research Center for Advanced Science and Technology, As, 先端技術研究センター, 助教授 (20222086)
Project Period (FY) 1997 – 1998
Keywords10nm InAs quantum dot / Self-assembly / Inverted HEMT structure / Memory function / Optical detector / Quantum point contact / Resonant tunnel structure / Capacitance-voltage spectroscopy
Research Abstract

Semiconductors (e.g., InAs) deposited on a lattice-mismatched substrate (e.g., GaAs) yields 10 nm-scale Quantum dots (QDs) spontaneously. We have exploited them to make memory devices, in which the presence and absence of a single electron in InAs QDs correspond to "1" and "0". We have also investigated electronic properties of such QDs.
First, we prepared an inverted high electron mobility transistors (HEMT), in which InAs QDs are embedded between the surface gate electrode and a two dimensional electron channel at the GaAs/n-AlGaAs heterojunction. By applying gate voltage (Vg) over 0.9 V, the threshold voltage of the transistor shifted to the positive side by DELTAV, resulting from the supply of electrons from the channel to QDs. This proves the feasibility of new memory effect. Analytical studies of transport characteristics have shown that each QD stores one electron each, since the Coulombic repulsion originating from the first trapped electron prevents the trapping of second electron. If the second electron is stored in the QD, it easily tunnels out from the QD.In addition, we studied the "write" and "erase" (i.e., charge and discharge) processes controlled by the light illumination. Further, we prepared and studied a prototype device of a quantum point contact, in which the charge trapping in QDs near the point contact leads to a clear hysteresis characteristics in the quantized conductance.
We have studied electronic levels of InAs QDs in AlGaAs layer by photoluminescence and capacitance-voltage spectroscopy. The quantized state in QDs was found to increase by ^- 200 meV when the Al content in AlGaAs barrier layer is raised. We clarified also the shape of wavefunctions of electrons confined in QDs by magneto-tunneling spectroscopy.

  • Research Products

    (22 results)

All Other

All Publications (22 results)

  • [Publications] G.Yusa: "MBE growth of novel GaAs/n-AlGaAs field effect transistor structures with embedded InAs quantum traps and their transport characteristics" Journal of Crystal Growth. 175/176. 730-735 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] G.Yusa: "Trapping of photogenerated carriers by InAs quantum dots and persistent phtoconductivity in novel GaAs/n-AlGaAs field-effect transistor structures" Appl.Phys.Lett.70(30). 345-347 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Inoshita: "Density of States and Phonon-Induced Relaxation of Electrons in Semiconductor Quantum Dots" Phys.Rev.B. 56.8. 4355-4358 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Inoshita: "Electro-Phonon Interaction and the So-Called Phonon Bottleneck in a Semiconductor Quantum Dots" Physica B. 227. 373-377 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 榊 裕之: "半導体ナノ構造の電子デバイス応用の展望" 電子情報通信学会誌. 80.7. 717-726 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] I.Kamiya: "Optical Properties of near surface-InAs quantum dots and their formation processes" Physica E. Vol.2. 637-642 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] G.Yusa: "Trapping of a single photogenerated hole by an InAs quantum dot in GaAs/n-AlGaAs quantaum trap FET and its spectral response in the near infrared regime" Physica E. Vol.2. 734-737 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.Qureshi: "Terahertz excitation of AFM-defined room temperature quantum dots" Phisica E. Vol.2. 701-703 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] I.Tanaka: "Imaging and probing electronic properties of self-assembled InAs quantum dots by atomic force microscopy with conductive tip" Appl.Phys.Lett.74.6. 844-846 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Yamauchi: "Electronic structure of nanometer-scale quantum dots created by a conductive atomic force microscope tip in resonant tunneling structures" Appl.Phys.Lett.74.11. 1582-1584 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] G.Yusa: "InAs quantum dot field effect transistors" Superlattices and Microstructures. 25.1/2. 247-250 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 榊 裕之(共著): "数理科学別冊「20世紀の物理学」" 数理科学, 188-195 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] G.Yusa, et al: "MBE growth of novel GaAs/n-AlGaAs field-effect transistor structures with embedded InAs quantum traps and their transport characteristics" J.Crystal Growth. Vol.175/176. 730-735 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] G.Yusa, et al: "Trapping of photogenerated carriers by InAs quantum dots and persistent phtoconductivity in novel GaAs/n-AlGaAs field-effect transistor structures" Appl.Phys.Lett.70 (3). 345-347 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Inoshita, et al: "Density of States and Phonon-Induced Relaxation of Electrons in Semiconductor Quantum Dots" Phys.Rev.B. 56 (8). R4355-4358 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Inoshita, et al: "Electro-Phonon Interaction and the So-Called Phonon Bottleneck in a Semiconductor Quantum Dots" Physica B. Vol.227. 373-377 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] I.Kamiya, et al: "Optical Properties of near surface-InAs Quantum Dots and their Formation Processes" Physica B. Vol.227. (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] G.Yusa, et al: "Trapping of a single photogenerated hole by an InAs quantum dot in GaAs/n-AlGaAs quantum trap FET and its spectral response in the near infrared regime" Physica E. Vol.2. 734-737 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.Qureshi, et al: "Terahertz excitation of AFM-defined room temperature quantum dots" Phisica E. Vol.2. 701-703 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] I.Tanaka, et al: "Imaging and probing electronic properties of self-assembled InAs quantum dots by atomic force microscopy with conductive tip" Appl.Phys.Lett.74 (6). 844-846 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M.Yamauchi, et al: "Electronic structure of nanometer-scale quantum dots created by a conductive atomic force microscope tip in resonant tunneling structures" Appl.Phys.Lett.74 (11). 1582-1584 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] G.Yusa, et al: "InAs quantum dot field effect transistors" Superlattices and Microstructures. Vol.25. 247-250 (1999)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-12-08  

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