Analysis of High Performing Terahertz Quantum Cascade Lasers

Detailed simulations for Terahertz quantum cascade lasers based on two-well designs are presented. We reproduce the maximal operation temperatures observed and attribute the degradation with temperature to the occupation of parasitic levels and thermal backfilling. Furthermore, we demonstrate that the current injection can be conveniently studied by using EZ states, which combine energy selectivity and spatial localisation. Improving the injection allows to achieve higher maximal operation temperatures around 265 Kelvin.