Reduction of threading screw dislocations in 4H-SiC crystals by a hybrid method with solution growth and physical vapor transport growth

Abstract

The propagation of defects during the hybrid growth, which combines solution growth and physical vapor transport (PVT) growth, for bulk 4H-polytype silicon carbide was examined. During solution growth, more than 80% of the threading screw dislocations (TSDs) were converted to defects on basal planes by formation of an 80-μm-thick TSD conversion layer. The layer thickness was limited by the balance between the conversion ratio and the surface roughness. During the subsequent PVT growth, most of the converted defects reverted to TSDs when the TSD conversion layer was planarized prior to PVT growth. In contrast, the converted defects were eliminated by continuous propagation on basal planes when the PVT growth was carried out on the as-grown surface of the TSD conversion layer. Microscopic imaging revealed that continuous formation of macrosteps in the PVT layer is essential for the elimination of the converted defects.