A T-Matrix Many-Particle Theory for Low-Dimensional Semiconductor Optics.

Abstract

In low-dimensional systems, quantum-confinement and bandstructure effects strongly influence the many-particle effects that ultimately give rise to the nonlinear optical properties of semiconductores. In this paper, we use a Keldysh Greens functions approach to obtain numerical results for isolated quantum wells and coupled superlattices, and investigate in different limits the combination of band-structure and many-particle effects. The inclusion of higher order Coulomb correlations gives rise to deviations from the results found in the literature for low carrier densities and temperatures, which increase with the fundamental band gap, and may be relevant for future optical device design and operation. The optical spectra presented illustrate the theoretical approach and provide insight on the physical mechanisms responsible for lasing in wide-band gap heterostructures, as contrasted to the usual 111-V systems.