Crystals of high structural perfection were investigated using several methods of X-ray diffraction topography in Bragg-case geometry. The methods included sectional and projection synchrotron white beam topography and monochromatic beam topography. The investigated 6H and 4H samples contained, over large regions, dislocations with a density that did not exceed 103/cm2. Most of them could not be interpreted as being hollow core dislocations (micro- or nano-pipes). The concentration of the latter was lower than 102/cm2. The present investigation confirmed the possibility of revealing dislocations with all used methods. The quality of presently obtained Bragg-case multi-crystal and section images of dislocation enabled analysis based on comparison with numerically simulated images. The analysis confirmed the domination of screw-type dislocations in the investigated crystals.

Observation of Individual Dislocations in 6H and 4H SiC by Means of Back-Reflection Methods of X-Ray Diffraction Topography. W.Wierzchowski, K.Wieteska, T.Balcer, A.Malinowska, W.Graeff, W.Hofman: Crystal Research and Technology, 2007, 42[12], 1359-63