Amorphous SiO2 precipitates at silicon grain boundaries

The structure and chemistry of a Sigma 33 grain boundary in a Si bicrystal were investigated as a function of thermal treatments. Amorphous SiO2 precipitates were found at the grain boundary. The precipitate interfaces are the {111} planes of the two crystals forming the boundary. The precipitate-crystal interfaces were studied by analytical transmission electron microscopy. The electronic states of the interfaces between the amorphous precipitates and the Si crystals are similar to those at the interface between Si and thermally grown SiO2 film. The electrical activity of the grain boundaries can be explained;based on these observations.