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

Room-temperature electroluminescence is obtained from erbium-doped Si diodes for heavily Er- and oxygen-doped material. Such diodes exhibit under reverse bias excitation a characteristic, about 10-20 nm wide emission spectrum which has a striking similarity to erbium-implanted silica (SiO(2) : Er) in contrast to the sharp line spectra of isolated Er centers seen at lower temperatures. The wide spectrum is thus attributed to the inhomogeneously broadened emission from Er in amorphous SiO(2-delta) precipitates. We show that the isolated centers can be transformed into Er-containing precipitates for sufficient Er- and O-doses by proper choice of the annealing temperature after implantation. (C) 1999 Elsevier Science B.V. All rights reserved.