Dynamical Screening, Collective Excitations, and Electron‐Phonon Interaction in Heterostructures and Semiconductor Quantum Wells. Application to Double Heterostructures

The collective excitations of a double heterostructure are examined in detail. Including the important effects of the interfaces of the system the uncoupled modes are analysed, which are the long‐wave optical interface phonon modes, LO phonon modes, and intra‐ and intersubband plasmon modes. The electron‐phonon interaction is discussed and the coupling functions are calculated and discussed in graphical form. The resulting coupled modes, intra‐ and intersubband plasmon‐phonon modes, are calculated for different approximations of the polarization function, the random‐phase approximation, the plasmon‐pol approximation, and the long‐wave approximation. The dispersion curves of these modes are presented in graphical form for various cases. It is shown that the Landau damping of the modes strongly depends on the layer thickness and the concentration of the quasi‐two‐dimensional electron gas.