Stress self-regulation model for high-speed epitaxy of large lattice mismatch systems

Close-spaced sublimation (CSS) is a cost-effective method for producing II-VI and III-V semiconductor epitaxial films at growth rates reaching hundreds of micrometers per hour. However, these thick films often suffer from a high density of microdefects, such as twins and threading dislocations (TDs), attributed to the interface mismatches and rapid growth rates. To achieve high-quality thick films, it is essential to further investigate the formation mechanisms of these microdefects. In this paper, we propose a stress self-regulation epitaxial model based on the growth of CdZnTe/GaAs(001) films. The lattice tilt of the CdZnTe islands provides initial stress alleviation in the mismatched heterojunctions, while the introduction of 60° dislocations from the island surfaces to the interface generates a driving force for lattice reorientation. Additionally, we reveal the role of dislocation glide in facilitating the transformation of twins into the matrix and its impact on the film interface. We discuss the relationships between stress relief and the formation of surface defects, such as growth pits and needles. The stress self-regulation epitaxial model highlights the importance of effective nucleation control for the development of high-quality epitaxial films, particularly in high-speed epitaxial processes. This research provides novel theoretical insights and experimental guidance for stress management and defect regulation in systems with large lattice mismatch.