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1998 Fiscal Year Final Research Report Summary

Coherent Phonon Quantum Dynamics in Semiconductor Nanostructures

Research Project

Project/Area Number 09450025
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Applied optics/Quantum optical engineering
Research InstitutionHOKKAIDO UNIVERSITY

Principal Investigator

WRIGHT Oliver B.  Grad.School of Eng., Hokkaido Univ., Pro., 大学院・工学研究科, 教授 (90281790)

Co-Investigator(Kenkyū-buntansha) TAMURA Shinichiro  Grad.School of Eng., Hokkaido Univ., Pro., 大学院・工学研究科, 教授 (80109488)
Project Period (FY) 1997 – 1998
KeywordsUltrafast / Semiconductor / Laser / Phonon / Ultrasound / Superlattice / Reflectance / Surface
Research Abstract

The main aim of this study is to extend our knowledge of ultrafast acoustic phonon generation using femtosecond light pulses to basic semiconducting materials and nanostructures. We use tightly focused excitation and probe light beams a few microns in diameter to allow the detection of coherent phonons with -1 mum lateral spatial resolution and sub-picosecond time resolution. In order to do this we have developed an ultrafast Sagnac interferometer for measurements at normal incidence.
The following studies were carried out :
1) Design and construction of a Sagnac interferometer for detection of coherent acoustic phonons on picosecond time scales. The design is particularly convenient for normal incidence measurements and is common path, rendering it immune to acoustic and thermal parasitic fluctuations.
2) Generation and detection of longitudinal coherent acoustic phonons in bulk GaAs (100). Above band-gap excitation and probe optical beams were incident from the same side of the sample. … More The effect of coherent phonon pulses propagating into the bulk was detected.
3) Generation and detection of longitudinal coherent acoustic phonons in ultrathin (<1 mum) GaAs (100) film (thickness 50 nm) on a Al_<0.3>Ga_<0.7>As (100) substrate film.(- 5 mum in thickness). Above band-gap excitation and probe optical beams were incident from opposite sides of the sample, allowing us to temporally separate phonon pulse signals from spurious thermal and purely electronic contributions to the signal.
4) Generation and detection of coherent acoustic phonons in periodic GaAs/AlAs superlattices. Superlattices with atomic order repeat lengths were probed. Selective excitation of the GaAs was achieved by tuning the pump beam to around 830 nm. A new excitation configuration, in which the superlattice was cleaved at right angles to the normal direction, was attempted. Signals due to the propagation of longitudinal acoustic phonons in the in-plane direction were observed.
In addition, theoretical work on metals carried out in parallel has allowed a first analytical treatment of the nonequilibrium relaxation of a free electron gas. Further work is needed to extend the technique to a wider variety of semiconductors and to higher frequency acoustic generation. up to - 10 THz. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] D. H.Hurley: "Detection of coherent phonon pulses by optical interferometry" Rev. Sci. Instrum. (to be published). (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D. H.Hurley: "Femtosecond generation of acoustic waves in GaAs" Ultrasonics(to be published). (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] O. B.Wright: "Electoron-phonon dynamics in metals on ultrashort timescales" Physica B(to be published). (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] O. B.Wright: "Ultrafast relaxation and diffusion of electrons in metals" 第5回フェムト秒テクノロジー国際ワークショップ(FST'98)、つくば. 147 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] V. E.Gusev: "Ultrafast nonequilibrium dynamics of electrons in metals" Phys. Rev. B. 57・5. 2878-2888 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] O. B.Wright: "金属中における電子の超高速緩和過程 : モンテカルロシュミレーションと理論的解析との比較" 日本物理学会1997年秋の分科会. 214 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] D.H.Hurley: "Detection of coherent phonon pulses by optical interferometry" Rev.Sci.Instrum.(to be published). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] D.H.Hurley: "Femtosecond generation of acoustic waves in GaAs" Ultrasonics. (to be published). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] O.B.Wright: "Electron-phonon dynamics in metals on ultrashort timescales" Physica B. (to be published). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] O.B.Wright: "Ultrafast relaxation and diffusion of electrons in metals" 'Proc.5th International Workshop on Femtosecond Technology, Tsukuba, Japan. 147 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] V.E.Gusev and O.B.Wright: "Ultrafast nonequilibrium Dynamics of electrons in metals" Phys.Rev.B57. 2878 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] O.B.Wright, P.L.G.Ventzek and V.E.Gusev: "Ultrafast athermal relaxation of electrons in metals : comparison of Monte Carlo and analytical methods" Proc.Autumn Conference of the Physical Society of Japan, Kobe, Japan. 214 (1997)

    • 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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