Exploring silicon [001] small angle symmetric tilt grain boundaries: Structures, energies and stress fields

A high efficient hybrid Monte Carlo and molecular dynamics (MC/MD) approach was carried out to reproduce silicon [001] small angle symmetric tilt grain boundaries at the atomic level. In the present paper, we concentrated on the variations of grain boundary properties under various misorientation angles, from which three critical misorientation angles were proposed and four grain boundary stages were divided to illustrate the structural transition of grain boundaries from small to large angle and the corresponding characteristics. The roles of dislocation stress fields in shaping some special grain boundary properties, such as dislocation structures and defect sink, were discussed. We also calculated three critical parameters (dislocation core radius, dislocation core energy and grain boundary width) about structures and energies of these studied grain boundaries, which would benefit the subsequent grain boundary engineering. Further investigations indicated that the three critical misorientation angles could be converted to the average distances of adjacent dislocations, which equalled to 6-, 2- and 1-times of dislocation core radius. Compared with the published literatures and classical theories, the simulations showed well accordance in structural units, stress fields and elastic strain energies.