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Abstract
We observe a long-range distortion field between parallel dislocations with opposite Burgers vectors in a platelet-shaped single crystal of 4H-SiC with a low dislocation density (~103 cm/cm3). This distortion field is in the µradian range when the distance D between dislocations is in the ~50–250 µm range. We were able to characterise this weak distortion field through Rocking Curve Imaging (RCI), a highly sensitive Bragg diffraction imaging technique using monochromatic synchrotron radiation. From the experimental images, we generate maps of the angle of maximum reflectance (“peak position”) that provide a measurement of the local lattice orientation. Deviations from the crystal matrix orientation are associated with the long-range distortion field around dislocations. Between parallel dislocations with opposite Burgers vectors, this distortion does not decay to zero but towards a constant value α. We propose a simple model considering the angular parameter α characterising the distortion. This model indicates that α should roughly vary as 1/D. This appears to be in fair agreement with our experimental data.
Highlights
The interaction between dislocations is a well-known topic, discussed in scientific literature since the middle of last century
The dislocations in 4H-SiC cannot move at room temperature, and we can consider their distance D as constant. When this distance D is in the range 50–250 μm, we observe a weak (~μradian) distortion of the region lying between parallel dislocations with opposite Burgers vectors
Our experiment shows that the region lying between parallel dislocations with opposite Burgers vectors exhibits an angular misorientation with respect to the crystal matrix
Summary
The interaction between dislocations is a well-known topic, discussed in scientific literature since the middle of last century. The dislocations in 4H-SiC cannot move at room temperature, and we can consider their distance D as constant. When this distance D is in the range 50–250 μm, we observe a weak (~μradian) distortion of the region lying between parallel dislocations with opposite Burgers vectors. Dislocations in 4H-SiC crystals have been extensively studied through X-ray diffraction Rocking Curve Imaging (see for instance [4,5,6,7,8,9]). We took advantage of the capabilities of Rocking Curve Imaging (RCI) [10] to perform this investigation.
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