A GREEN-FUNCTION THEORY OF PLASMONS IN 2-DIMENSIONAL SEMICONDUCTOR STRUCTURES - FINITE MAGNETIC-FIELD

A theoretical investigation has been made of the magnetoplasmon excita tions in several two-dimensional (2D) semiconductor structures subject ed to an applied magnetic field in the framework of a Green-function ( or response function) theory. The applied magnetic field Bo is assumed to be oriented parallel to the interfaces and perpendicular to the di rection of propagation (Voigt geometry). The material layers are chara cterized by frequency-dependent dielectric function and the quantum-si ze effects are ignored. The Green-function theory generalized to be ap plicable to the 2D systems enables us to derive explicit expressions f or the corresponding response functions (associated with the electroma gnetic fields) which can in turn be used to calculate almost all physi cal properties of the system at hand. A simple analytical diagnosis of the general results for all the systems investigated here leads us to reproduce exactly the previously well-established results, for the di spersion relations for plasmons and magnetoplasmons. obtained within a different theoretical framework. As examples, we have incorporated nu merical results on the dispersion characteristics of magnetoplasmons i n several geometries. It is found that the excitation spectrum in the Voigt geometry contains a complete magnetic-field-dependent gap within which no magnetoplasmons are allowed to propagate. The simplicity and the compact forms of the desired results give the present theory a wi dth of interest. The implications of the analytical and numerical resu lts have been discussed briefly. (C) 1998 Academic Press.