Defect structures at the GaAs/Si interface after annealing

High-resolution electron microscopy was applied to investigate the effect of post-annealing on the defect structure at the GaAs/Si interface. This study indicates that annealing results in dislocation rearrangement at the interface to form the majority of Lomer’s dislocations with their Burgers vectors parallel to the interface. Dislocations with inclined Burgers vectors (type 2) at the interface after annealing are often observed at steps introduced by the substrate surface roughness. This observation is discussed in terms of the shrinking of stacking faults and microtwins and the preferential nucleation of both stacking faults (or microtwins) and type 2 dislocations at surface steps.