GROWTH DEFECT STUDIES IN SIC SINGLE-CRYSTALS

Growth defects in vapor grown 6H-SiC single crystals have been studied using a combination of techniques, including: synchrotron white beam x-ray topography (SWBXT), conventional optical microscopy, fluorescenc e microscopy, and epi-fluorescence laser scanning confocal microscopy (LSCM). These studies of crystal sections cut both parallel and perpen dicular to the [0001] growth axis focused on growth dislocations of sc rew character running approximately parallel to the growth axis. SWBXT back-reflection and transmission images are presented of these disloc ations, which are known to possess a range of Burgers vector magnitude s, and in the case of large Burgers vector magnitude, hollow cores, kn own as micropipes. Results of detailed LSCM and fluorescence microscop y imaging of these micropipes are presented and discussed in the light of the SWBXT images. Detailed SWBXT studies further reveal that slip dislocations lying in the (0001) plane are connected to the growth dis locations, and appear to emanate from them, periodically along their l engths, in the form of loops. The periodicity, along the superscrew di slocations, of these dislocation generation phenomena, is found to be very similar to the periodicity of dilation and constriction phenomena in the associated micropipes, as measured by LSCM and fluorescence mi croscopy. This suggests that tile two phenomena may be related.