Dynamical Formation Process of Pure Edge Misfit Dislocations at GaAs/Si Interfaces in Post-Annealing

We investigate the dynamical formation process of pure edge misfit dislocations (90° type) in GaAs/Si(100) (3° off toward [011]). The cross sections at the interfaces of GaAs/Si annealed at various temperatures (300–600° C) are observed by high-resolution transmission electron microscopy. The pure edge dislocation is formed by the reaction of two mixed dislocations (60° type) at the interface, and is not introduced directly from the epilayer surface. To explain the experimental results, we present a new formation process of pure edge dislocations: (1) glide from the epilayer surface, (2) climb along the interface and (3) reaction. In this process, the climb motion along the interface is most important. In addition, the difference in the ratio of pure edge dislocations to the total dislocations was observed between stepped and flat directions of the Si substrate. This asymmetry may be caused by the difference in climb velocities along the interface. The Si surface steps probably enhance this climb motion.