Intervalley Scattering and the Role of Indirect Band Gap AlAs Barriers: Application to GaAs/AlGaAs Quantum Cascade Lasers

We report on the results of our simulations of Γ - X scattering in GaAs/AlGaAs heterostructures, discussing the importance of the mole fraction, doping density, and lattice and electron temperature in determining the scattering rates. We consider three systems, a single quantum well (for the investigation of Γ - X scattering), a double quantum well (to compare the Γ - X - G and Γ - T scattering rates), and an example of a GaAs/AlGaAs mid-infrared quantum cascade laser. Our simulations suggest that Γ - X scattering can be significant at room temperature but falls off rapidly at lower temperatures. One important factor determining the scattering rate is found to be the energy difference between the Γ- and X-states.