On the generation of optically active Er centers in Si light emitting diodes

Room-temperature electroluminescence is obtained from erbium-doped Si diode s for heavily Er- and oxygen-doped material. Such diodes exhibit under reve rse bias excitation a characteristic, about 10-20 nm wide emission spectrum which has a striking similarity to erbium-implanted silica (SiO2 : Er) in contrast to the sharp line spectra of isolated Er centers seen at lower tem peratures. The wide spectrum is thus attributed to the inhomogeneously broa dened emission from Er in amorphous SiO2-delta precipitates. We show that t he isolated centers can be transformed into Er-containing precipitates for sufficient Er- and O-doses by proper choice of the annealing temperature af ter implantation. (C) 1999 Elsevier Science B.V. All rights reserved.