Non-radiative ionization of perturbation centres by means of excitons in semi-conducting and dielectric crystals

Abstract

Non-radiative ionization of a perturbation centre formed by an electron trapped in the Coulomb field of the perturbation by means of excitons of large radius in semi-conducting and dielectric crystals is theoretically investigated. It is shown that such non-radiative ionization may occur by two processes: the direct non-radiative transfer of the excitation energy from the exciton to the electron of the perturbation and by exchange non-radiative ionization whereby the electron on the perturbation recombines non-radiatively with the hole in the exciton and the electron of the exciton with the energy released during this recombination passes to the ionized state of the perturbation.The corresponding probabilities per sec and recombination coefficients are calculated as a function of the concentration of perturbation centres and the type of exciton according to its optical origin. The result is used for a theoretical estimate of the influence of perturbation centres of the given type on the optical life-time of the exciton.