A simple semi-phenomenological model, which accurately predicts the dependence of threshold
current for temperature of Resonant-phonon three well quantum cascade laser based on vertical
transitions is offered. We found that, the longitude optical phonon scattering of thermally excited
electrons is the most important limiting factor for thermal performance of high frequency THz QCLs.
In low frequency region, parasitic current increases the threshold current. Based on our model the use
of materials with higher longitude optical phonon energy such as InGaAs/GaAsSb and decreasing the
lower laser level lifetime can increase the maximum performance temperature. Our observations may
can be used to understand the notion of the effects of thermal electrons on reduction of laser