It was recalled that the annihilation of grown-in defects by H annealing was often explained in terms of the dissolution of O precipitates. This was because it was generally assumed that grown-in defects in Czochralski-type crystals were very large O precipitates. It was pointed out here that it was necessary to reconsider this mechanism for the annihilation of defects by H annealing because it had recently been shown that the grown-in defects were voids of octahedral shape. A simulation model was presented here which described the annihilation of void defects during H annealing.

K.Nakamura, T.Saishoji, J.Tomioka: Applied Physics Letters, 1997, 70[26], 3525-7