Donor activity of ion-implanted erbium in silicon

Abstract

Hall measurements performed in the temperature range 4–300 K on Er + implanted silicon revealed the existence of shallow and deep donor states. Samples implanted with Er + alone show a shallow level at 8–14 meV below the conduction band edge and a deep level at 60–100 meV. Coimplantation with O + or S + shifts the levels deeper into the gap or introduces additional donor levels. The concentration of the shallow level depends on implantation and annealing parameters and amounts up to 10% of the implanted Er. It is suggested that the donor levels play an important role for the excitation and deexcitation processes of the Er luminescence in Si.