Dislocation patterning and bunching in crystals and epitaxial layers ‐ a review

Abstract

Cellular patterning and dislocation bundling as structures of dislocation dynamics in as‐grown crystals and epitaxial layers are reviewed. Selected examples of multicrystalline (mc) silicon, III‐V and II‐VI compounds are presented. The origins of often overlaid dislocation networks varying by the cell scale and cell wall design are reported. The introduction in selected phenomenological fundamentals shows that dynamical polygonization basing on dislocation glide cannot be the only possible formation process. Even at high temperatures the point defect assisted climb plays a decisional role in the dislocation dynamics. Dissipative structuring via non‐equilibrium thermodynamics is considered. Reduction of thermo‐mechanical stress and control of stoichiometry are practical counter measures. Special attention is paid to the dislocation banding and their pile‐up at grain boundaries leading to dislocation bunching. On the other hand at heteroepitaxial processes the controlled banding of dislocations is used to grow out them laterally. Further, second phase inclusions are responsible for dislocation accumulations. Their incorporation must be avoided by good mixing of the fluid phase and composition control. The required bridge intensification between crystal growers and metal physicists as well as the need of in situ experiments and advanced numeric modeling is underlined.