Mapping of individual dislocations with dark-field X-ray microscopy

Abstract

This article presents an X-ray microscopy approach for mapping deeply embedded dislocations in three dimensions using a monochromatic beam with a low divergence. Magnified images are acquired by inserting an X-ray objective lens in the diffracted beam. The strain fields close to the core of dislocations give rise to scattering at angles where weak beam conditions are obtained. Analytical expressions are derived for the image contrast. While the use of the objective implies an integration over two directions in reciprocal space, scanning an aperture in the back focal plane of the microscope allows a reciprocal-space resolution of ÁQ/Q < 5 Â 10 À5 in all directions, ultimately enabling highprecision mapping of lattice strain and tilt. The approach is demonstrated on three types of samples: a multi-scale study of a large diamond crystal in transmission, magnified section topography on a 140 mm-thick SrTiO 3 sample and a reflection study of misfit dislocations in a 120 nm-thick BiFeO 3 film epitaxially grown on a thick substrate. With optimal contrast, the half-widths at half-maximum of the dislocation lines are 200 nm. A. C. Jakobsen et al. Mapping of dislocation networks 127 Figure 5Projection images of a large single-crystal diamond in the transmission experiment. (Left) Nearfield detector image with no X-ray objective and (right) corresponding dark-field image acquired with the diffraction microscope, both for À 0 = 0.002 . The magnification of the microscope is M ¼ 16:2. The direction of the rotation axis is marked by an arrow.q q 2 andq q roll are parallel to the x and y axes of these subfigures, respectively.

X‐Ray Topography—More than Nice Pictures

“…Such a high sensitivity allows the resolution of 20 nm sized details in integrated circuits. [113] But X-ray ptychography [114] and a variety of other high sophisticated X-ray microscopy and diffraction based imaging methods [115,116,117] are another story, which would go beyond the scope of this article.…”

Role of threading dislocations on the growth of HgCdTe epilayers investigated using monochromatic X-ray Bragg diffraction imaging

“…The brighter parts indicate higher intensity. Images recorded on the tails of the rocking curve correspond to 'weak-beam' conditions, which are widely used to enhance the contrast of defects such as dislocations, notably in dark-field microscopy and XBDI (Cockayne et al, 1969;Fung et al, 1997;Jakobsen et al, 2019;Sauvage et al, 1980). Let us start with Fig.…”

Improved grain mapping by laboratory X-ray diffraction contrast tomography

“…Several techniques have been developed at third-generation synchrotron X-ray facilities for such characterization. These include differential aperture X-ray microscopy (Larson et al, 2002), 3D X-ray diffraction microscopy (Poulsen et al, 2001;Poulsen, 2004Poulsen, , 2012 and its variants like high-energy X-ray diffraction microscopy (Suter et al, 2006), scanning 3D X-ray diffraction microscopy (Hayashi et al, 2015;Henningsson et al, 2020) and diffraction contrast tomography (DCT) (Ludwig et al, 2008;Reischig & Ludwig, 2020), as well as dark-field X-ray microscopy (Simons et al, 2015;Jakobsen et al, 2019;Poulsen, 2020). These methods allow grain mapping at different length scales.…”