Photoluminescence from Si : Er under front and backside excitation

Photoluminescence (PL) of Si:Er samples was investigated in two experimenta l configurations, the excitation beam from an argon-laser was applied eithe r from the Er-implanted, or from the opposite side of the sample. In both c ases the same PL spectrum, dominated by the so-called 'cubic' Er-related ce nter, was observed. Significant differences were found in excitation power dependence, and in kinetics of PL signal measured in the two configurations . The difference in the power dependence indicates energy loss in the bulk of the sample. A pn-junction created in the p-type sample upon Er implantat ion was considered as a possible origin of the differences observed in kine tics of Er-related photoluminescence. In addition to these effects, a slowl y decaying Er-related photoluminescence was observed to appear under backsi de illumination. It is argued that it might represent the true radiative li fetime of Er ion embedded in silicon crystalline matrix. (C) 2001 Elsevier Science B.V. All rights reserved.