Measurement of dislocation core distribution by digital processing of high-resolution transmission electron microscopy micrographs: a new technique for studying defects

Abstract

A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects, is employed for digital image processing of high-resolution transmission electron micrographs. The procedure starts with the geometric phase method for extracting the lattice distortion field near dislocation cores. Next, the dislocation core distribution (DCD) is recovered from the lattice distortion field. A so-obtained DCD field takes non-zero values only in disordered regions of the lattice. The accuracy of this method is investigated by mathematical integration of the dislocation field over core regions to find the in-plane components of the Burgers vectors. The proposed method is free of topological problems and can be used to study spatial configurations of complex defects in large crystal areas by using a fully automatic computer program. This approach is applied to investigate a network of misfit dislocations in the interfacial region of a GaAs/ZnTe/CdTe heterostructure.

Extracting Quantitative Information from High Resolution Electron Microscopy

“…The geometrical phase method has now been used for the analysis of distortion fields around a defect or defect networks as was shown for misfit dislocations in GaSb/GaAs [69] and in CdTe/GaAs [70] or for interaction of threading dislocations and prismatic stacking faults in GaN [71]. It also has been valuable for the calculation of strain fields in hetero-epitaxial pseudomorphic multilayers like CdTe/ZnTe [72], Co/NiO [73].…”

Nanoscale waviness of low-angle grain boundaries

“…Phase analysis has been used to accurately measure displacements around a [100] dislocation in olivine to Ͻ0.09 Å (6) and a [110] dislocation in Si to 0.03 Å (7). The technique also has been used to examine the distribution of dislocations along heterophase interfaces and LAGBs in semiconducting materials (8,9). Here we employ the phase technique to analyze LAGBs in naturally deformed olivine, a widespread rock-forming mineral that is an important constituent of Earth's upper mantle and crust.…”

Local rotations due to mixed‐type misfit dislocation at α‐Fe2O3/α‐Al2O3 heterostructure interface

“…In recent years, a new method based on the combination of high‐resolution transmission electron microscopy (HRTEM), geometric phase analysis (GPA) and dislocation density tensor analysis has been developed to investigate partial dislocations (Kioseoglou et al ., ) and misfit dislocations (Kret et al ., ; Wang & Ruterana, ; Wang et al ., ). The atomic configuration, strain mapping, dislocation density distribution and Burgers vectors of dislocations can be obtained simultaneously by this method.…”

“…This method, proposed by Kret et al . () during the investigation of misfit dislocations in GaAs/CdTe interface, starts with the GPA for extracting the lattice distortion field near dislocation cores from HRTEM. Next, the dislocation density distribution is calculated from the lattice distortion filed.…”