Observations of melting phenomena were carried out in situ by using an ultra-high voltage electron microscope. Lattice defects which were introduced by rapid cooling from a partly molten state were examined in detail by means of conventional transmission electron microscopy. Stacking fault tetrahedra were found to form; thus indicating that the clustering and collapse of thermal vacancies took place on {111} planes at high temperatures. The formation mechanism was suggested to involve the condensation of thermal vacancies on a {111} plane, which then resulted in the creation of a Frank-type dislocation loop and its subsequent dissociation into stair-rod dislocations plus Shockley partial dislocations on the other 3 inclined sets of {111} planes.

Formation of stacking-fault tetrahedra in silicon rapidly solidified from the melt R.Oshima, F.Hori, M.Komatsu, H.Mori: Japanese Journal of Applied Physics - 2, 1998, 37[12A], L1430-2