Hot phonon effect in resonant-phonon-assisted terahertz quantum-cascade lasers

We have studied the hot electron and phonon transport in resonant-phonon-assisted terahertz (THz) quantum-cascade lasers (QCLs) by using the semiclassical Monte Carlo method. The hot phonon effect is included in the Monte Carlo simulation by introducing a time constant accounting for the decay of polar optical phonons into other phonon modes. It is found that nonequilibrium polar optical phonons may modify the electron-phonon interaction, affect the electron distribution in different subbands, and consequently change the device current.