The effect of post-implantation annealing conditions upon the electrical and optical properties of Er-implanted material was studied. The observed dependence of the photoluminescence intensity, donor center concentration, Er activation coefficient and Er-doped layer thickness upon the annealing conditions showed that, as well as Er and O atoms, intrinsic point defects which were generated during annealing participated in the formation of optically and electrically active centers. The relationship between the electroluminescence intensities of free excitons and of Er ions was found to depend upon the pumping current. It was suggested that the excitation of Er ions occurred via the capture of free excitons on neutral Er-related donor levels, with a subsequent Auger-excitation of the f-shell of the Er ion during recombination of a bound exciton.

N.A.Sobolev, O.V.Alexandrov, M.S.Bresler, O.B.Gusev, E.I.Shek, M.I.Makoviichuk, E.O.Parshin: Materials Science Forum, 1995, 196-201, 597-602