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

Abstract

The atomically resolved structure of misfit dislocations (MDs) at heterovalent II−VI/III−V (001) compound semiconductor interfaces has been determined using aberrationcorrected 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.

STEM Tools for Semiconductor Characterization: Beyond High-Resolution Imaging

“…The extracted data is highly valuable to explain the growth mechanism of semiconductor nanostructures, polarization effects, optical properties or piezo-electric behavior [ 25 ], to list some examples. Detailed structural and chemical analysis can be conducted at heterointerfaces, including in-depth studies of structural defects [ 26 ]. Facing more complex semiconductor alloy compositions, where every atomic column may be composed by more than one atomic specie, i.e., quaternary III-V alloys, as dilute nitrides, requires from other analytical strategies.…”