X-Ray Topographic Studies of Defects in PVT 6H-SiC Substrates and Epitaxial 6H-SiC Thin Films

Synchrotron white beam X-ray topography has been used to characterize defect structures in (0001) 6H-SiC substrates grown by the sublimation physical vapor transport (PVT) technique as well as in 6H-SiC epitaxial thin films grown on these substrates. Defects revealed in 6H-SiC substrates include super screw dislocations and basal plane dislocations. It has been found that back-reflection topographs are particularly suitable for imaging such super screw dislocations as well as basal plane dislocations whenever transmission topography is not applicable. Epitaxial 6H-SiC thin films grown on such (0001) substrates (tilted a few degrees towards the a-axis) were also examined by using surface sensitive grazing Bragg-Laue topography. It has been shown that super screw dislocations were replicated in the epitaxial thin films but no basal plane dislocations were revealed in the thin films. Results from various topographic techniques are discussed.