Influência de interação coulombiana entre portadores no espectro de luminescência de semicondutores de GAP direto

Abstract

Basic aspects of the optical behaviour of an electronhole plasma (EHP) in highly excited semiconductors and the influence of the Coulomb interaction between carriers on the luminescence spectrum of direct gap semiconductors (in the parabolic'band approximation) are analysed. A chain of equations for collective Double-Time Green functions are obtained without considering the Theorem of Asymptotical Decoupling (ADT). These are then decoupled in the Random Phase Approximation (RPA), what enables the obtention of the imaginary part of the relevant Green Function in a self - consistent way. As basic results, one can point a shift of the luminescence peak to regions of lower energies and the broadenning ofthe spectrum as the excitation intensity increases. On the other hand, it is also shown that, in addition to the energy gap renormalization, the Coulomb interaction is also responsible for a structure in the high energy side of the EHP luminescence spectrum, which, nevertheless, doesn't appear in the gain - absorption spectrum, in agreement with experimental results.