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een derived, by which the problems of reflection andtransmission for the electromagnetic wave inmultilayers structures composed from cholesteric liquidcrystals have been solved emphasising in the repeatedreflection on the space between layers. Further,dependence of the reflection spectrum on thepolarization of the incident beam are determined whenthe incident beam perpendicular to the surface ofmultilayers structures composed from fourteen layerswhich consists of consecutive one-by-one components,one from cholesteric liquid crystal layers, other fromdielectric layers. Moreover dependence of thepolarization of the reflection wave and the transmissionwave on wavelength are obtained when the incidentbeam is in quadrature with system of the cholestericliquid crystal putting on an isotropic dielectric layer.Người trình bày: Phạm Thùy Dung41. The Channel-Width Dependence Of The Low-Temperature Hole Mobility In Ge-rich NarrowSquare Quantum Well Studied by the BandbendingMethodTrần Thị Hải, Nguyễn Trung Hồng, NguyễnHuyền Tụng, Đoàn Nhật QuangWe employ the theory of band-bending effects to explainthe channel-width dependence of the mobility of a twodimentionalhole gas (2DHG) in narrow squareSi/Si¬1-xGex/Si quantum well at high Ge content. Thenumerical calculation of scattering mechnisms is shownin comparision with the one from the previousThành phố Đồng Hới (03- 06/8/2009) Trang 47/ 102computation. As a result. Our method enables a beterquantitative description of recently measured data aboutthe dependence of the 8 K mobility of holes in aSi/Si¬0.2Ge0.8/Si quantum well on the channel widthvarying from 25-70A.Người trình bày: Trần Thị Hải42. Electron-Phonon Resonance and AbsorptionLine-widths in Quantum WiresLê Đình, Nguyễn Đình Hiên, Lê Văn Hưng, TrầnCông PhongElectrophonon resonance (EPR) and optical detectedelectrophonon resonance (ODEPR) effects areinvestigated in rectangular and cylindrical quantumwires using the projection operator technique. Weobtain the analytical expressions and graphs ofabsorption power. From graphs of the absorption powerwe obtain linewidths as profile of curves. Byconsidering the dependence of shift of absorption peaksin the case of electron –phonon resonance on thefrequency of incident photon we determine theconditions of ODEPR. The dependence of theseconditions on temperature, wire’s parameters has beenanalyzed. A comparison between effects occurring in thetwo types of wire has been also considered.Người trình bày: Nguyễn Đình Hiên43. The Nonlinear Acoustoelectric Effect in aSuperlatticeThành phố Đồng Hới (03- 06/8/2009) Trang 48/ 102