THE USE OF SYNCHROTRON-RADIATION X-RAY-DIFFRACTION TOPOGRAPHY TO DETERMINE THE SPATIAL-DISTRIBUTION OF POLYTYPES AND ONE-DIMENSIONAL DISORDER IN SIC

Novel experimental techniques are described for studying the spatial d istribution of polytypes in multipolytypic SiC crystals. These methods provide information on adjoining long-period polytypes and the interv ening boundaries and their relationship to one-dimensional disorder. W ith the improved resolution of second-generation synchrotrons it is no w possible to unravel complex multipolytype edge profiles. These are r evealing previously unseen features, such as high defect density bands and fine one-dimensionally disordered layers at polytype boundaries.