Theory of a strained p-Ge resonant-state terahertz laser

A theory of a strained p-Ge resonant-state THz laser is developed. A comprehensive study of the processes leading to the stimulated THz emission in strained p-Ge under an electric field applied is presented. The distribution functions of light and heavy holes are found. The scattering by optical and acoustic phonons, as well as resonant scattering by charged impurities are taken into account. The steady-state hole distribution functions are used to calculate the generation-recombination coefficients which enter into the system of rate equations for the localized states populations. The populations of localized and resonant acceptor states are found. The conditions for population inversion are investigated. The optical gain calculation is carried out taking into account main optical transitions in the THz spectrum range.