Dislocation cross-slip in heteroepitaxial multilayer films

We simulated dislocation dynamics in heteroepitaxial multilayer thin film systems, considering the case where threading dislocations emerging from the substrate replicate themselves into the thin film during the film growth process. In the regime where the thin film layer thickness is tens of nanometers, the strain hardening mechanism involves the glide of single threading dislocation segments in the thin film instead of by dislocation pile-ups. We studied the dislocations' evolution behavior and their interactions since these then became significant to the strain hardening of the multilayer structure. Cross-slip of threading dislocation segments in multilayer structure was found to be more prevalent compared to a single-layered thin film. This can result in a more complex pattern of interfacial dislocations and may have a significant contribution to the interactions between threading and interfacial dislocations. The simulation was carried out using the level set method incorporating thin film growth.