Double longitudinal-optical phonon intrawell depopulated terahertz quantum cascade structures: Electron transport modeling using a density matrix method

Abstract

Terahertz quantum cascade structures using double longitudinal-optical phonon intrawell scattering for depopulation are theoretically studied. A density matrix Monte Carlo method is used to calculate the temperature dependent optical power, in double phonon structures with diagonal optical transitions. It is shown that using depopulation transitions greater than the resonant longitudinal-optical phonon energy ΔE > ℏωLO reduces the phonon absorption thermal backscatter, allowing for higher operating temperatures, with prospects for 300 K room temperature and beyond. Furthermore, results indicate that the temperature limit may also be improved in single phonon structures, by similarly increasing the depopulation transition.