Hot carrier effect on resonant state THz laser operation

A comprehensive theoretical study of the operation of the strained hot hole p-Ge RSL is performed. Hot hole kinetics in strained p-Ge under an applied electric field is studied and heavy and light hole distribution functions are found as a solution to the Boltzmann kinetic equation, which includes interactions with acoustic and optical phonons, as well as resonant and nonresonant ionized impurity scattering. Nonequilibrium population of the localized acceptor states is obtained as a solution to the system of rate equations within the two-level model for an impurity level structure. Conditions for the formation of the intracentre population inversion are studied as a function of the electric field and external strain. We have observed that the population inversion is formed in a wide range of electric fields and, therefore, could be easily achieved. Net gain at the THz frequencies is calculated using the nonequilibrium hot hole distribution function and the localized states population. The possibility of achieving net THz gain in semiconductors by injection of hot carriers into impurity resonant states is demonstrated.