Effect of Injector Doping on Non-Equilibrium Electron Dynamics in Mid-Infrared GaAs/AlGaAs Quantum Cascade Lasers

The aim of this work is to report a detailed theoretical investigation, supported by the experimental measurements, of the influence of the injector doping level on the output characteristics and the working range limits in mid-infrared GaAs/AlGaAs quantum cascade lasers. A fully self-consistent Schrodinger - Poisson analysis based on the scattering rate equation approach was employed to simulate the above-threshold electron transport in the device. An onset of v-shaped local band edge bowing has been observed, preventing the resonant subband level alignment in the high pump current regime. The observed saturation of the maximal current, together with an increase of threshold current, limits the dynamic working range for higher doping levels.