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1993 Fiscal Year Final Research Report Summary

Investigation of Photo-Response in Micro-structure Device of Photo-conducting Semiconductor and Superconductor

Research Project

Project/Area Number 03452040
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 固体物性
Research InstitutionOsaka University

Principal Investigator

TAKAOKA Sadao  Faculty of Science, Osaka University, Associate Professor, 理学部, 助教授 (50135654)

Project Period (FY) 1991 – 1993
KeywordsSuperconductivity Proximity Effect / Josephson Junction / Mesoscopic System / Quantum Hall Effect / Edge State / Two Dimensional Electron System / Persistent Photoconductivity
Research Abstract

In order to investigate the influence of illumination on the superconductivity proximity effect between superconductor and photo-conducting semiconductor, we have made the mesoscopic devices from a pair of Pb, In, Au multi-layr superconducting films on indium doped Pb_<1-x>Sn_xTe (x=0.25) semiconductor single crystal. The electron mobility is very high and the amount of persistent photoconductivity is large in indium doped Pb_<1-x>Sn_xTe, which indicates that the penetration length of superconductivity into semiconductor is long and could be varied widely. We measured the superconducting characteristic of these devices under illumination. In the devices with the gap width between the superconductor films below 0.2-0.3mum, the hysteresis in the current-voltage curve is observed at 4.2K, which is a typical characteristic of Josephson junction. Further the critical current (the sudden increase point of resistance) increases with increaseing illumination. From these results, we succeed in changing the superconducting characteristic of the mesoscopic device by illumination.
Using an AC resistance bridge, which was purchased by this grant, we have also measured magnetic field dependence of capacitance in a two dimensional electron system (GaAs/AlGaAs heterostructure) in the quantum Hall regime. It has been found that the bottom values of capacitance at the Hall plateaus are determined not by the gate area but by the edge length of the gate. These results can not be explained by the conventional interpretation of magnetocapacitance, where the capacitance is directly related to the density of states of a two dimensional electron gas. We suggest a model that the bottom values are determined by the area of edge states. From this model, the widths of edge states were estimated and compared with the recent theory.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] S.TAKAOKA: "“Ballistic and Elastic Mean Free Paths Determined by Magnetic Electron Focusing Effect in GaAs/AlGaAs"" Solid State Communications.83. 775-777 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.TAKAOKA: "“Influence of Gate Voltage on Nonlocal Resistance in GaAs/AlGaAs Heterostructure at High Magnetic Fields"" Physica B. 184. 21-25 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.TAKAOKA: "“Magnetocapacitance and the Edge State in a Two Dimensional Electron System in Quantum Hall Regime"" Physical Review Letters.(印刷中).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 小新堂 透: "「半導体-超伝導体接合での超伝導近接効果に対する光伝導の影響」" 物性研究. 56. 566-596 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 鷹岡 貞夫: "「光に応答する超伝導材料」" 大阪大学低温センターだより. 76. 6-10 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 邑瀬 和生: "「半導体-金属複合系の量子伝導」" 生産技術誌. 45. 12-18 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] S.Takaoka: ""Ballistic and Elastic Mean Free Paths Determined by Magnetic Electron Focusing Effect in GaAs/AlGaAs"" Solid State Communications. vol.83. 775-777 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S.Takaoka: ""Influence of Gate Voltage on Nonlocal Resistance in GaAs/AlGaAs Heterostructure at High Magnetic Fields"" Physica B. vol.184. pp.21-25 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S.Takaoka: ""Magnetocapacitance and the Edge State in a Two Dimensional Electron System in Quantum Hall Regime"" Physical Review Letters. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T.Koshindo: ""Influence of Photoconduction on Superconductivity Proximity Effect in Semiconductor-Superconductor Junction" (in Japanese)" Bussei-Kenkyuu. vol.56. 566-596 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] S.Takaoka: ""Superconducting Material to Respond to Light" ( in Japanese)" Osaka University Teion-Center-Dayori. vol.76. 6-10 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Murase: ""Quantum Conduction in Semiconductor-Superconductor Composite System" (in Japanese)" Seisan-Gijutu-Si. vol.45. 12-18 (1993)

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

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Published: 1995-03-27  

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