| Project/Area Number |
10650051
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
NISHIGUCHI Norihiko Hokkaido Univ., Grad. School of Eng., Asso. Pro., 大学院・工学研究科, 助教授 (40175518)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yukihiro,Norihiko Hokkaido Univ., Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (00281791)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | acoustic phonons / phonon focusing / semiconductor films / phonon prism effect / フォノン / プリズム効果 |
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| Research Abstract |
In order to search for possible use of a semiconductor film as 'phonon prism' for spectral analysis of phonons in solids, phonon focusing effects in GaAs films were investigated by means of xyz algorithm developed in the resonant ultrasound spectroscopy. Dispersion relations of the normal modes of the acoustic waves are known as Ramb waves depend on the propagating directions due to the elastic anisotropy of the films. The Poynting vector of the Ramb waves change its direction on frequency, in particular, when the wavelength becomes the same order of the film thickness. Hence it seems that the phonon focusing effect is found to be useful for the frequency analysis of the acoustic phonons. However, there is a difficulty in resolution of the phonon spectrum due to subband structure of dispersion relation. The subband structure is originated from quantization of wave vector in the normal direction of the films. The normal modes have their own dispersion relations, and then the group velocities of the modes are different even at the same frequency, mixing of the acoustic waves.
A possible method to resolve them based on the polarization of the waves was examined, but it was found to fail since the waves have the same polarization except for the wavenumber in the normal direction of the film. Another possible application of the phonon focusing in the thin films and a method to resolve the phonons are under consideration.
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