Dislocation junctions as barriers to threading dislocation migration

Level set simulations of dislocation dynamics in biaxially strained, heteroepitaxial films reveal interesting kinetic and thermodynamic mechanisms for blocking the migration of threading dislocations. Two dislocations on the same or on intersecting slip planes may react to form a threading dislocation segment that does not glide under the influence of the misfit strain. In the coplanar case, a kinetic barrier exists that slows down dislocation migration. For the reaction involving dislocations on intersecting planes, an energetic barrier impedes other advancing dislocations. These barriers create significant and frequent impediment to threading dislocation flow, resulting in pileups and high threading dislocation densities.