Laser scattering tomographic twin defects were directly observed for the first time, in as-grown wafers, by means of transmission electron microscopy. The shapes of the grown-in defects, as estimated from transmission electron microscopic images, were octahedral or tetrahedral; with side-walls lying in the {111} plane. The sizes of the grown-in defects were of the order of 100nm. The O concentration within the grown-in defects was close to the detection limit of energy-dispersive X-ray spectrometry. Nevertheless, it was shown that there were significant differences in the O contents of the defects. That is, the volume of grown-in defects was nearly free of O while a significant amount of O was detected within O precipitates. It was proposed that voids in the crystalline lattice formed via the agglomeration of vacancies during the growth and/or cooling of Czochralski-type crystals.

M.Nishimura, S.Yoshino, H.Motoura, S.Shimura, T.Mchedlidze, T.Hikone: Journal of the Electrochemical Society, 1996, 143[10], L243-6