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 Gamma-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 Gamma-X scattering), a double quantum well (to compare the Gamma-X-G and Gamma-Gamma scattering rates), and an example of a GaAs/AlGaAs mid-infrared quantum cascade laser. Our simulations suggest that Gamma-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 Gamma- and X-states.