Capturing Dislocation Half-Loop Formation and Dynamics in Epitaxial Growth Atomistically at Diffusive Time Scales

A structural phase-field crystal (XPFC) model is employed to simulate the atomistic mechanisms associated with defect nucleation in mismatched heteroepitaxial growth. Crucially, this approach utilizes a mean-field density field that resolves atomistic features but evolves on diffusional time scales relevant to epitaxial growth. It is used to investigate different degrees of mismatch at the “million atom” level. The half-loop dislocation behavior exhibited by the model is shown to be consistent with experiments reported in the literature. Through this approach we are able to provide key insights into the dislocation half-loop nucleation stage and its relation to both the conditions of the substrate employed and other defects present in the epitaxial layer. In general, this methodology provides an important bridge between atomistic and classical concepts dealing with half-loop dislocation formation and propagation. More broadly, the methodology presented seeks to aid experimental control over dislocation formation in high-quality lattice-mismatched electronic devices.