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Linear and nonlinear photoeleastic coefficients in superlattices with tilted energy band profiles Host Publication: International Congress on Ultrasonics Authors: R. Ayukhanov, G. Shkerdin, V. Kotov and J. Stiens Publication Date: Apr. 2007
Abstract: The influence of quantum well (QW) bottom inclination on resonant photoelastic properties of quantum superlattices near the ground exciton resonances has been studied theoretically. Analytical expressions for dielectric permittivity and photoelastic constants were analytically derived for the cases of both QW bottom inclination stimulated by electrical field applied to QW (electrical inclination) and QW bottom inclination produced by the change of QW chemical composition (vari-gap inclination). It was shown that for both cases linear and nonlinear photoelastic constants depend on factor , where is the superlattice period, is the variation parameter calculated to determine the wave function and energy of ground exciton state. It was shown that < ( is the variation parameter for QW without bottom inclination) for the vari-gape inclination case and > for the electrical inclination case. In the case of electrical inclination electron and hole are shifted to the opposite direction inside a quantum well and electron-hole pairs localization decreases. On the contrary electron-hole pairs localiza-tion increases in the case of vari-gape inclination. For this reason vari-gap inclination of QW bottom results in resonant photoelastic constants increase and electrical inclination of QW bottom results in resonant photoelasticity constants decrease. It was shown that the main contribution to the resonant photoelastic constants in QW structures near the exciton resonance is con-nected with the exciton energy modulation by the acoustic wave as a result of electron-phonon interaction via deformation potential. Numerical calculation results of photoelastic constants for GaAS/AlxGa1-xAs superlattices with in-clined bottom are presented in the paper.
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