On the Formation and Multiplicity of Si [001] Small Angle Symmetric Tilt Grain Boundaries: Atomistic Simulation of Directional Growth

Grain boundary (GB) is the fundamental issue enabling the high performance of multicrystalline materials. However, structural multiplicity within some macroscopic GB characters may significantly affect their microscopic properties. In this paper, the natural formation process of a Si [001] small angle (1.15 degrees) symmetric tilt GB is reproduced via molecular dynamics, where we find three dislocation types and six GB-dislocation structures. The dislocations are observed as the sink of defects during the GB formation, and their formation probabilities are strongly correlated with the elastic strain energy. For more potential structural multiplicity, a lower misorientation angle is energetically favorable. The validity of our results is confirmed by the continuum theory.