A molecular dynamics study of nucleation of dislocation in growth of silicon from melt

• First MD simulation of dislocation formation in growth of Si from melt.
• Reveal difference in dislocation formation in growths along 〈100〉, 〈110〉 and 〈112〉.
• Trace back in atomistic scale to very beginning of a dislocation forming process.
• Identify phenomenal correlation between faceting, twinning and high probability of dislocation formation.

Molecular dynamics (MD) simulations of growths of crystalline silicon from the melt along 〈100〉, 〈110〉 and 〈112〉 directions have been carried out. Tersoff potential is employed for computing atomic interaction. The results show that in the growths along 〈100〉, 〈110〉, no dislocation was formed, while in the growth along 〈112〉, more than one dislocations formed. The dislocation formed is identified as a partial dislocation lying on an {111} plane, with segments of 30° partial dislocation, 90° partial dislocations and some kinks. The dislocation nucleates stochastically at the crystal/melt interface, where atoms interact with each other to form at least two units of stable periodic non-six-member-ring groups. Once formed, it extends with the crystal growth, with its two ends attached to the crystal/melt interface. The 〈112〉 growth distinguished from the 〈100〉 and 〈110〉 growths by its prone-to-{111}-faceting and twinning, which may be the cause of the significantly higher probability of dislocation nucleation in the 〈112〉 growth.