The influence of doping concentration on split-well resonant-phonon terahertz quantum cascade lasers.

This study explores the effect of doping density on the performance of split-well resonant-phonon (SWRP) Terahertz Quantum Cascade Lasers (THz QCLs) through non-equilibrium Green's functions (NEGF) analysis. Experimental research showed that increasing the doping concentration in these designs led to better results compared to the split-well direct-phonon (SWDP) design, which has a larger overlap between its active laser states and the doping profile. We also found that electron-electron (e-e) scattering is a major factor in performance limitation. By identifying key scattering mechanisms, we propose optimization strategies for doping profiles and material quality to enhance operational temperatures. This research offers insights into overcoming current limitations in THz QCLs, setting a foundation for future technological advancements.