A Green-Function Theory of Plasmons in Two-Dimensional Semiconductor Structures: Finite Magnetic Field

• Published in: Annals of physics 1998-05, Vol.265 (1), p.1-51
• Main Authors: Kushwaha, M.S., Djafari-Rouhani, B.
• Format: Article
• Language: English
• ISSN: 0003-4916; 1096-035X
• DOI: 10.1006/aphy.1998.5780

A theoretical investigation has been made of the magnetoplasmon excitations in several two-dimensional (2D) semiconductor structures subjected to an applied magnetic field in the framework of a Green-function (or response function) theory. The applied magnetic field B→0is assumed to be oriented parallel to the interfaces and perpendicular to the direction of propagation (Voigt geometry). The material layers are characterized by frequency-dependent dielectric function and the quantum–size effects are ignored. The Green-function theory generalized to be applicable to the 2D systems enables us to derive explicit expressions for the corresponding response functions (associated with the electromagnetic fields) which can in turn be used to calculate almost all physical 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 dispersion relations for plasmons and magnetoplasmons, obtained within a different theoretical framework. As examples, we have incorporated numerical results on the dispersion characteristics of magnetoplasmons in 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 width of interest. The implications of the analytical and numerical results have been discussed briefly.