Scattering channels in high temperature terahertz quantum cascade structures

The effects of scattering channels in high operating temperature terahertz quantum cascade laser structures are studied. The electron transport is calculated using a density matrix Monte Carlo method, where the scattering channels are isolated to determine their effects by including and excluding each channel in the transport calculations. Scattering channels leaking to the continuum and from the longitudinal-optical phonon interaction are considered. All channels investigated except one are found to decrease the maximum operating temperature, and only phonon backscattering to the upper lasing state enhances thermal performance. Improving the isolation of scattering channel states is expected to further increase the operating temperature, with thermal backfilling to the lower lasing state dominating.