Secondary cracking at grain boundaries in silicon thin films

In this article, we report irregular cleavage front transmission at grain boundaries in free-standing polysilicon thin films. When the orientations of two adjacent grains are correlated, the crack may bypass the boundary via a “tunneling” process. Similar behavior can also be achieved if the crack path curves in the grain-boundary-affected zone. Moreover, the separation of crack flanks can be aided by secondary cracking. These irregular modes of crack front behavior tend to lower the effective boundary toughness.