Influence of Injector Doping Concentration on the Performance of InP-Based Quantum-Cascade Lasers

The influence of injector doping concentration N_inj on the performance of InP-based quantum-cascade (QC) lasers is investigated for devices emitting around 9.2-mum wavelength and injector doping concentrations between 1times10¹⁷ cm^-3 and 3times10¹⁷ cm^-3. The threshold current density, the dynamic range, the maximum emitted output power as well as the maximum operating temperature are found to increase with increasing N _inj. All in all, there exists no optimal value of N_inj per se. In fact, the injector doping concentration has to be adjusted individually depending whether emphasis is placed on obtaining low threshold current densities or on high-power operation