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Title: Sense Determination of Micropipes via Grazing-incidence Synchrotron White Beam X-ray Topography in 4H-Silicon Carbide

Grazing-incidence synchrotron topography studies of micropipes (MPs) and closed-core threading screw dislocations (TSDs) have been carried out and the results compared with ray-tracing simulations. Simulations indicate that both MPs and TSDs appear as roughly elliptically shaped white features which are canted to one side or the other of the g-vector depending on the dislocation sense and which have asymmetric perimeters of dark contrast which are greatly enhanced on the side towards which the feature is canted (again depending on the dislocation sense). For MPs, observations are generally consistent with this although the cant of the features is more obviously discerned than the asymmetry in the perimeter contrast. Sense assignment for MPs has been validated using back-reflection reticulography. For TSDs, observation are again generally consistent with the simulations although the smaller feature size and the variability in the line direction of the TSDs make the asymmetry of perimeter contrast a more obvious and reliable way to determine the dislocation sense than the sense of cant. TSD dislocation senses so obtained were validated using back-reflection images of same-sign and opposite-sign pairs.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
980447
Report Number(s):
BNL--93365-2010-JA
Journal ID: ISSN 0255-5476; MSFOEP; TRN: US1005499
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Science Forum; Journal Volume: 600-603
Research Org:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org:
Doe - Office Of Science
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ALLOCATIONS; ASYMMETRY; BEAMS; CARBIDES; DISLOCATIONS; IMAGES; SCREW DISLOCATIONS; SIZE; SYNCHROTRONS; TOPOGRAPHY national synchrotron light source