Role of elastic scattering mechanisms in GaInAs∕AlInAs quantum cascade lasers

Electron scattering spectroscopy has been performed on a GaInAs∕AlInAs midinfrared quantum cascade laser by applying a strong magnetic field along its growth axis. The interpretation of the experimental data, supported by our model of the electron lifetime in the presence of a strong magnetic field, very clearly demonstrates that the elastic contribution to the total scattering rate has a weight comparable to that of the optical phonons. The authors believe that this contribution has its origin in the alloy disorder, an efficient mechanism in this material system, which limits the lifetime of the excited subband of the laser transition.