The restricted random dislocation distribution model to describe ensembles of dislocations with a screw component in ZnO layers with a mosaic structure

Abstract

By applying the restricted random dislocation distribution model, solved using a discrete Hankel transform approach, it is shown that the shapes and characteristics of the ω-scans of the ZnO 00.2 reflection are mainly determined by the strain field introduced by dislocations with a screw component. On the other hand, no clear evidence of mosaicity or interfacial region contributions is found despite the layers exhibiting a c axis oriented residual columnar structure and a highly defective interface being present. The applied model not only permits a more precise estimation of the densities of dislocations, which present a screw component with respect to methods based on the analysis of the 00.2 peak ω-scan FWHM, but also gives an indication of their distribution characteristics with the extracted values, as well as their homogeneous/quasi-regular spacing, being confirmed by cross-sectional transmission electron microscopy observations.