The investigation of temperature degradation in THz quantum cascade lasers based on resonant-phonon design

We have designed and fabricated terahertz quantum cascade lasers (THz QCL) based on GaAs/A1
_0.15
Ga
_0.85
As three and four-quantum well active module with resonant-phonon depopulation scheme. Three-well and four-well THz QCLs have a lasing frequencies of 3.2 and 2.3 THz, respectively. We investigate the dependence of threshold current and lasing output power on temperature. The investigation of temperature degradation in THz QCLs shows that the thermally activated longitudinal optical-phonon scattering is the dominant mechanism.