Simulation of THz Quantum Cascade Lasers

Abstract: Quantum Cascade Lasers (QCLs) have since their invention in 1994 become a crucial source for mid-infrared and THz radiation. Mid-infrared QCLs have achieved room temperature operation while THz QCLs have not. As such, simulations are an important tool in order to achieve a THz QCL operational at room temperature. This work uses a simulation package based on a nonequilibrium Green’s function model to investigate which Conduction Band Offset (CBO) should be used for the most accurate results and if there is a difference between samples from different labs. These CBOs are then used to simulate current the state-of-the-art THz QCLs, which is done with great success. For example, the thermal degradation of the QCLs was analyzed and showed that thermal backfilling and thermally activated leakage channels were the main cause. Also, new QCLs were designed from the information gained. Two of these samples are predicted according to the simulation package to outperform the current best performing QCLs.