Er and O have been coimplanted in silicon. Rutherford backscattering and channeling analysis show that after annealing the Er profiles are different for the samples with various O doses. For the sample of high O dose

after annealing Er profile is same as the one before annealing

and the sample recrystallization is perfect. For the sample of middle O dose

after annealing Er profiles present two peaks. We consider that Er-O complexes form during annealing. The formatiom of complexes reduces the Er segregation and diffusivity and influences the Er redistribution profiles. A series of experiments of Er and O implantation doses confirm the crucial role of O in increasing Er

3+

luminescence.