A tool for automatic recognition of [110] tilt grain boundaries in zincblende-type crystals

Abstract

The local atomic structure of [110] tilt grain boundaries (GBs) formed in a100anm-sized GaAs nanocrystals, which crystallize in the non-centrosymmetric zincblende-type structure with face-centred cubic lattice symmetry, was imaged and analysed by means of high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The nanocrystals were grown by metal-organic vapour phase epitaxy on top of (001) Si nanotips embedded in an oxide matrix. This paper introduces an automatic analysis method and corresponding processing tool for the identification of the GBs. The method comprises (i) extraction of crystallographic parameters, i.e. misorientation angles and transformation matrices for the different crystal parts (grains/twins) observed by HAADF-STEM, and (ii) determination of their common plane(s) by modelling all possible intersections of the corresponding three-dimensional reciprocal lattices. The structural unit model is also used to characterize the GB structures and to validate the data obtained by the developed algorithm.An automated analysis approach for recognition of grain boundaries in face-centred cubic based zincblende materials from high-resolution high-angle annular dark-field scanning transmission electron microscopy images is described and its performance is tested.