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Observation of individual dislocations in 6h and 4h sic by means of back-reflection methods of x-ray diffraction topography

Wojciech Wierzchowski 1Krzysztof Wieteska 2Tomasz Balcer 1Agnieszka Malinowska 1,3Władysław Hofman 1Walter Graeff 4

1. Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland
2. Institute of Atomic Energy, Otwock-Świerk 05-400, Poland
3. Warsaw University of Technology, Faculty of Physics, Koszykowa 75, Warszawa 00-662, Poland
4. Hamburger Synchrotronstrahlungslabor HASYLAB (HASYLAB), Notkestrasse 85, Hamburg D-22603, Germany


The Bragg-case geometry is less popular in topographic experiments than the transmission geometry, because in some cases the visibility of individual dislocations can be lowered. Otherwise it can be often very useful, e.g. providing more transparent images at higher concentration of defects.

In the present work we investigated SiC crystals of high structural perfection with several methods of X-ray diffraction topography in Bragg-case geometry. The methods included section and projection ones as well as single crystal and double crystal methods exploring conventional and conventional sources of X-ray diffraction. The investigated 6H and 4H monopolytypic SiC wafers were manufactured by CREE and in large regions they contained the dislocation density on the level not exceeding 103 cm-2 which cannot be interpreted as hollow core dislocations (micro- or nano-pipes). The concentration of the last ones was lower than 102 cm-2.

The present investigation confirmed the possibility of revealing dislocations with all used methods, including most inconvenient case of single projection topography in Cu Ka1 radiation. The character of the images was significantly different in case of different topographic methods. The images of dislocation in synchrotron and conventional multi-crystal arrangement consisted of characteristic rosettes with a “tail” coming from the dislocation core, while single crystal projection topographs provided the images of dislocation in form of characteristic dots or commas and section images reproduced the dislocations in form of black rosettes.

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.


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Related papers

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Wojciech Wierzchowski
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-24 00:10
Revised:   2009-06-07 00:44