NICKEL DISILICIDE PRECIPITATES AT AN ASYMMETRIC TILT SIGMA = 9 GRAIN-BOUNDARY IN SILICON

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