Influence of Doping Density on Two-Well Injector Terahertz Quantum Cascade Lasers

This study explores the impact of doping density on the temperature performance of two-well injector direct-phonon (TWI-DP) terahertz quantum cascade lasers (THz QCLs) through both experimental analysis and Non-Equilibrium Green's functions (NEGF) simulations. While previous research suggested that increasing doping density could enhance performance, the findings indicate that higher doping densities do not improve temperature performance due to increased electron-electron (e-e) scattering, which outweighs the benefits of reduced ionized impurity scattering (IIS). The research emphasizes the need for precise doping optimization and suggests future design improvements, such as optimizing injection coupling and modifying barrier composition, to achieve a better high-temperature THz lasing performance.