Sub-grain induced crack deviation in multi-crystalline silicon

Abstract

The fracture process in crystalline silicon is dictated by energy dissipation. Here, we show that sub-grains can deviate the crack path from the most energetically favorable (111) plane. Albeit a small misorientation across the sub-grain boundary is identified, upon entering into the sub-grain region, the crack either slightly deviates from the ideal (111) plane or directly chooses the secondly most favorable (110) one. We propose that the deviation is related to the dislocation core in the (111) crystal plane, which leads to a discontinuous atom debonding process and consequently a pronounced lattice trapping. In this circumstance, localized crystal defects prevail in the fracture process of silicon, while energetical criterion fails to interpret the crack path.