Atomic-Resolution Structure Imaging of Misfit Dislocations at Heterovalent II-VI/III-V Interfaces

The atomically resolved structure of misfit dislocations (MDs) at heterovalent II-VI/III-V (001) compound semiconductor interfaces has been determined using aberration-corrected electron microscopy. The MDs at an ZnTe/InAs interface, which has small lattice mismatch (Δa/a ∼0.74%), are primarily 60° glide-set dislocations, with unpaired atomic columns at the dislocation cores mostly containing indium. Lomer dislocations observed at the ZnTe/InP interface (Δa/a ∼3.85%) consist of a 10-atom ring and two 5-atom rings, whereas shuffle-set Lomer dislocations observed at the ZnTe/GaAs interface (Δa/a ∼7.4%) have symmetrical 5/7-atom ring structures, although asymmetrical and disordered Lomer core structures are sometimes observed. Intensity line profiles across defect-free regions of the heterointerfaces indicate substantial interfacial intermixing. Thus, unpaired atomic columns at the MD cores are likely to consist of mixed atomic species.