A photoluminescence investigation was made of Czochralski-grown monocrystals which contained a ring-shaped distribution of oxidation-induced stacking faults. After 2-step annealing, at 800 and 1000C in N, dislocation-related D-lines were observed. These lines were attributed to dislocations which were generated from O precipitates that were produced by the 2-step annealing. The intensities of the D-lines in the ring area were weaker than those in other areas. This corresponded with the observation that the density of O precipitates in the ring area was lower than that in other areas. A strong dependence of spatial variations in the photoluminescence intensity, upon the penetration depth of the excitation light, indicated that the dislocations around O precipitates were more closely correlated with the ring area in region which were further from the surface.

K.Terashima, T.Ikarashi, H.Ono, M.Tajima: Materials Science Forum, 1995, 196-201, 1129-34