Optically active erbium centers in silicon

The intra-4f transition close to 1.54 mu m of Er implanted into Si shows rich fine structure due to the crystal field of different defect types. Making use of the influence of implantation and annealing parameters, additional doping, temperature, and excitation power, we identify groups of lines belonging to different Er-related, optically active defects: the isolated interstitial Er, axial symmetry Er complexes with oxygen, and Er complex centers containing residual radiation defects. We show that the exciton binding energies as well as nonradiative quenching rates differ for different Er centers. Under optimum annealing conditions, the isolated interstitial Er has the highest photoluminescence yield at temperatures above 100 K.