Homogeneous broadening in quantum dots due to Auger scattering with wetting layer carriers

The homogeneous broadening in semiconductor quantum dot (QD) lasers and optical amplifiers is studied theoretically. Based on a model for the electronic states of the coupled QD-wetting layer (WL) system, Coulomb interaction matrix elements are calculated, including both screening and exchange interaction. The homogeneous broadening due to various Auger processes, involving scattering of carriers between WL states and confined QD states, is calculated. The effects of the orthogonalization of WL states, QD confinement, QD density, and carrier density on the homogeneous broadening are studied systematically. We found that such WL-assisted Auger scattering is very efficient with subpicosecond dephasing times, and it is the dominant channel for the homogeneous broadening at high carrier density. Good agreement is achieved when comparing our theoretical results and recent experimental data. © 2005 The American Physical Society.