Defect / distortion characterisation of crystals and deposited layers: new capabilities using quantitative X-ray Bragg diffraction imaging

Start Date
01-07-2019 10:00
End Date
01-07-2019 11:00
Room 500 - 501, Central Building
Speaker's name
Speaker's institute
Contact name
Eva Jahn
Host name
Veijo Honkimaki
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X-ray Bragg diffraction imaging (“topography”) entered into practical use when Lang[1] designed an “easy” technical setup to characterise the defects / distortions in the high perfection crystals produced for the microelectronics industry. The use of this technique extended to all kind of high quality crystals, and deposited layers, and a series of publications explained, starting from the dynamical theory of diffraction, the contrast of the images of the defects.

A quantitative version of “monochromatic topography” known as “Rocking Curve Imaging” (RCI) was implemented, by using synchrotron light and taking advantage of the dramatic improvement of the 2D-detectors and computerised image processing. The rough data is constituted by a number (~ 300) of images recorded along the diffraction (“rocking”) curve. If the quality of the crystal is such that a one-to-one relation between a pixel of the detector and a voxel within the crystal can be established (this approximation is very well fulfilled if the local mosaic spread of the voxel is < 1 mradian), a software we developed provides, from the each rocking curve recorded on each of the pixels of the detector, not only the “voxel” integrated intensity (the only data provided by the previous techniques), but also its “mosaic spread” (FWHM) and peak position. We will show, based on many examples, that this new data, never recorded before, open the field to a highly enhanced characterization of the crystal and deposited layers. These examples include the characterization of dislocations and twins occurring during silicon growth, and the characterisation of the defects within deposited layers, or their effect on the diamond substrate.


1 A  reference book for dynamical theory, Borrmann effect and diffraction topographic techniques (excluding RCI) is : André Authier, Dynamical Theory of X-Ray Diffraction, Oxford university Press (2001)


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