Nickel disilicide precipitates at an asymmetric tilt Σ = 9 grain boundary in silicon

An asymmetric Σ = 9 twin boundary is extracted from a B-doped polycrystalline silicon ingot contaminated with nickel and copper. It is studied using electron beam induced current (EBIC) in the scanning electron microscope (SEM), on the one hand, and analytical transmission electron microscopy (AEM), on the other hand. This grain boundary is decorated mainly with nickel disilicide precipitates, which are shown to induce a high electrical activity. These particles appear to exhibit simple epitaxial relationships with one of the grains only, allowing one to conclude that nucleation preferentially occurs on this side of the GB plane.