Misorientation and Temperature Dependence of Small Angle Twist Grain Boundaries in Silicon: Atomistic Simulation of Directional Growth

In nano-crystalline and multi-crystalline silicon, grain boundaries (GBs) and their properties may dominate the overall material performance. With a hybrid Monte Carlo and molecular dynamics (MC/MD) approach capable of reproducing the natural formation process of silicon (001) small angle twist GBs, the misorientation and temperature dependence of GB properties were examined at the atomic level. The GB structures and energies show various transition characteristics around three critical misorientation angles. Structure–property correlations are established by converting the three critical misorientation angles to the corresponding dislocation spacings, which are equal to 6-, 2-, and 1-times dislocation core radius. Stress fields and elastic strain energies agree well with the Continuum theory, and their effects on the dislocation structures and defect sink are discussed. This work also reports the variations of GB structures and energies are governed by a critical temperature at around 800 K, where the GB energies reach the minimum and the dislocation dissociations are suppressed.