The stress birefringence images of low angle grain boundaries in 6H-SiC single crystals

摘要

Low angle grain boundaries, also referred to as domain walls, is one of the major structural defects in c-axis physical vapor transport (PVT) grown hexagonal Silicon Carbide. To investigate the nature of the low angle boundaries, polarized optical microscope was used. The low angle boundary gives bright stress birefringence images under polarizing optical microscope. Periodic extinction of the stress birefringence images occurs when the (0001)-face SiC is rotated under polarizing optical microscope. The micro-structure of the low angle boundary is proposed. Using dislocation elastic theory, it is theoretically confirmed that the domains consist of uniform pure edge dislocations with Burgers vectors perpendicular to the dislocation arrays. The simulation results coincide with the experimental observations.