Abstract
Employing an ensemble Monte Carlo transport simulation, we self-consistently analyze the spectral gain for different terahertz quantum cascade laser structures, considering bound-to-continuum as well as resonant phonon depopulation designs. In this context, we investigate temperature dependent gain broadening, affecting the temperature performance of terahertz structures. Furthermore, we discuss the influence of the individual scattering mechanisms, such as electron-electron, impurity and interface roughness scattering. A comparison of the simulation results to experimental data yields good agreement. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3147943]