ANALYSIS OF THE PHENOMENOLOGICAL MODELS FOR LONG-WAVELENGTH POLAR OPTICAL MODES IN SEMICONDUCTOR LAYERED SYSTEMS

The standard type of phenomenological model for this problem consists of a mechanical field equation for the vibration amplitude and-in the quasistatic limit-Poisson's equation. The critical issue concerns the matching boundary conditions. The apparent incompatibility between mechanical and electrostatic boundary conditions often appearing in the literature is analyzed and clarified. It is shown how the full solution can be obtained so that there is no incompatibility and the key features of the results, notably the symmetry pattern, agree with microscopic calculations and with Raman-scattering data.