High-resolution electron microscopy was used to study the atomic structure of As precipitates which formed in low-temperature samples during high-temperature annealing. Almost all of the precipitates, after annealing at 850 and 950C, were found to be twinned; with a {¯11•4} twin plane. Twinning was associated with the crystallization of amorphous or liquid-like As precipitates during cooling. The nucleation of rhombohedral As appeared to be most favourable on the short facet that was parallel to the {111}B plane. Twin formation usually nucleated on the long facet which was bounded by the {111}A plane. Crystallization usually ended in a void, due to shrinkage of the As volume during solidification.

S.Ruvimov, C.Dicker, J.Washburn, Z.Liliental-Weber: Applied Physics Letters, 1998, 72[2], 226-8