SOME ASPECTS ON INTERFACE MODES AND LO EIGENMODES IN GAAS/ALAS QUANTUM-WELLS

The interface modes and LO phonon modes in GaAs/AlAs quantum wells is investigated within the isotropic dispersionless dielectric continuum with nodes in displacement u at the interfaces as boundary condition. The interface modes are found to be purely interface polarization charge effect while LO eigenmodes induce only bulk polarization charges. Analytical expression is determined for LO eigenmodes and is found in good agreement with realistic model calculation, and its labeling index is interpreted as the helicity of electric field as it travels from one side to the other side of the slab.