Theory of amplification of eigenmode acoustic surface waves in thin bismuth films
Chhi-Chong Wu; Jensan Tsai; Chhi-Chong Wu; Inst. of Electron., Nat. Chiao Tung Univ., Hsinchu, Taiwan; Jensan Tsai; Inst. of Electron., Nat. Chiao Tung Univ., Hsinchu, Taiwan
Журнал:
Journal of Physics: Condensed Matter
Дата:
1990-06-25
Аннотация:
Amplification characteristics of eigenmode acoustic waves in thin bismuth films are investigated quantum-mechanically in the gigahertz frequency region. Numerical results show that the amplification coefficient for the P-SV mode (pressure wave-shear wave with vertical polarisation) oscillates with the frequency in the higher-frequency region, and these oscillations diminish as the temperature decreases. For the SV-P mode (shear wave with vertical polarisation-pressure wave), the amplification coefficient oscillates with the frequency in the higher-frequency region for the EP (ellipsoidal parabolic), ENP (ellipsoidal nonparabolic) and MNENP (modified nonellipsoidal nonparabolic) models, but no oscillations can be observed for the NENP (nonellipsoidal nonparabolic) model. These oscillations also diminish as the temperature decreases. No amplification can be observed for the SH mode (shear wave with horizontal polarisation) in thin bismuth films. For the TR mode (total reflection), no oscillations of the amplification coefficient can be observed, and this appears to be the same property as that for Rayleigh waves.
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