Auger deexcitation of Er3+ ions in crystalline Si optically induced by midinfrared illumination -: art. no. 035213

We report on the de-excitation of Er3+ ions in crystalline silicon, induced by midinfrared radiation from a free electron laser. The effect is interpreted as an Auger energy transfer between excited erbium ions and free holes in the valence band. These are liberated from shallow traps by the powerful mid infrared laser beam. The traps are dynamically populated during the initial band-to-band excitation. The efficiency of the proposed de-excitation mechanism depends on the number of traps occupied at the moment when the free electron laser pulse is applied. Therefore the quenching effect is sensitive to the total number of acceptor traps present in the sample and the excitation density of the pump pulse. A competition between this de-excitation process and the previously reported mid infrared-induced Er photoluminescence enhancement is investigated. The optically induced Auger process, as revealed in this study, complements the description of energy transfer processes in the Si:Er system under optical pumping.