Excitation and de-excitation of Yb3+ in InP and Er3+ in Si: photoluminescence and impact ionization studies

In the paper the existing information on the optical excitation of the erbium ion in crystalline silicon is critically reviewed. The proposed excitation mechanism is compared to the one which is believed to be responsible for the luminescence of ytterbium in indium phosphide. To this end the influence of constant and microwave electric field on the photoluminescence of both systems is inspected. It is shown that, although both systems show some similarities, their analogy is limited. The particular role of excitons and electrons in both the excitation as well as the de-excitation mechanism is investigated for the Si:Er system. The results of photoluminescence decay studies (T=4.2 K) are presented. It is argued that a nonradiative energy transfer to conduction electrons is responsible for the limitation of the energy transfer to the Er core and for its nonradiative recombination. Also, a prominent role of excitons in the energy transfer mechanism is confirmed. Finally, the origin of the 873 meV photoluminescence band recently reported in Er-implanted Si is discussed in relation to a possible defect-mediated activation of Er.