Interface phonon modes in quantum cascade lasers

We investigate the interface phonon assisted transition in GaAs/AlGaAs quantum cascade lasers (QCLs) by using the transfer matrix method based on the dielectric continuum model. Electron eigenvalues and eigenstates are calculated by solving Schrodinger equation and the Poisson equation self-consistently. The AlAs-like and upper GaAs-like interface phonon modes contribute most of the scattering rate. Interface phonon modes couple strongly with electrons at E-2, and the magnitude of scattering rate between E-2 and E-1 is much larger than that between E-3 and E-1, which is helpful for the laser inversion between E-3 and E-2. The calculation can be easily applied to the design and simulation of QCLs.