Coulomb scattering in the Monte Carlo simulation of terahertz quantum-cascade lasers

The authors compare different Coulomb screening models in the Monte Carlo simulation of terahertz quantum-cascade lasers: the static multisubband screening model and two single subband models. In quantum-cascade structures, electrons are located in many different subbands. Coulomb screening from all these subbands influences the intra- and intersubband scattering processes. The simulation results show that one of the two single subband models overestimates the screening effect, while the other underestimates it. The authors show the reasons for this and propose simple modification to the single subband models.