Faceting of twin grain boundaries in polysilicon films

The faceting of grain boundaries (GB) under annealing in phosphorus-doped polysilicon films, produced by low-pressure chemical vapor deposition, has been investigated by transmission electron microscopy. It has been shown that the facet types and facet density depend on annealing temperature. It has been found that GB facets are generally parallel with close-packed planes in coincidence site lattice. A correlation between GB faceting and grain-growth mechanisms has been considered. It has been shown that faceting takes place both under normal and abnormal grain growth. It is revealed that twinning plays the key role for GB faceting under normal grain growth.