Features in the impurity photoconductivity spectra ofn-GaAs andn-InP at energies multiple of the optical phonon energy

We report the experimentally revealed peculiarities in the impurity photoconductivity spectra of bulk n-GaAs and n-InP samples doped with shallow impurities. These features are essentially the photoconductivity steps at the photoexcitation quanta energies near (2, 3, 4, 5) · ℏωLO, where ℏωLO is the energy of the longitudinal optical phonon. A theoretical description of the observed peculiarities is proposed. It is shown that the photoconductivity features are determined by the energy dependence of the rate of electron energy relaxation.