Dislocation Formation From a Polycrystal Free-Surface

The introduction of a dislocation from the free-surface of a grain A of a polycrystal has been investigated from the theoretical point of view. Assuming two disclination dipoles are lying in a high angle boundary separating the corresponding grain A and a neighbor grain B, the equilibrium position of the dislocation has been determined in the grain A versus the separation distance between the two dipoles, the length and strength of each dipole.

Formation of Dislocations in the Growth of Silicon along Different Crystallographic Directions—A Molecular Dynamics Study

Molecular dynamics simulations of the seeded solidification of silicon along <100>, <110>, <111> and <112> directions have been carried out. The Tersoff potential is adopted for computing atomic interaction. The control of uniaxial strains in the seed crystals is enabled in the simulations. The results show that the dislocation forms stochastically at the crystal/melt interface, with the highest probability of the formation in <111> growth, which agrees with the prediction from a previously proposed twinning-associated dislocation formation mechanism. Applications of the strains within a certain range are found to inhibit the {111}-twinning-associated dislocation formation, while beyond this range they are found to induce dislocation formation by different mechanisms.