Rocking Curve Imaging Investigation Of The Long-Range Distortion Field Between Parallel Dislocations With Opposite Burgers Vectors

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 (similar to 10(3) cm/cm(3)). This distortion field is in the mu radian range when the distance D between dislocations is in the similar to 50-250 mu m 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 alpha. We propose a simple model considering the angular parameter alpha characterising the distortion. This model indicates that alpha should roughly vary as 1/D. This appears to be in fair agreement with our experimental data.