Monocrystalline Czochralski-type samples were studied, using photoluminescence, transmission electron microscopic, and chemical etching/Nomarski microscopic techniques, after 1MeV Er implantation to a dose of 1013/cm2 and annealing (1100C, 0.25 to 3h) in Ar- or Cl-containing ambients. It was found that annealing in a Cl-containing ambient gave rise to dislocation loops and pure edge dislocations. Pure edge dislocations were responsible for the appearance of lines in the photoluminescence spectrum. The Er-related lines which were due to intra-4f shell transitions in the rare-earth ions predominated in the photoluminescence spectra, and no structural defects were observed after annealing in Ar. The differences in the optical and structural properties of Er-doped material were attributed to intrinsic point defects that were generated during implantation and annealing.

N.A.Sobolev, O.B.Gusev, E.I.Shek, V.I.Vdovin, T.G.Yugova, A.M.Emelyanov: Applied Physics Letters, 1998, 72[25], 3326-8