Sublimation growth of silicon carbide bulk crystals:: experimental and theoretical studies on defect formation and growth rate augmentation

SiC crystals of 30-40 mm diameter were grown by physical vapor transport (PVT). The defect generation during seeding and subsequent growth was investigated. The main origin of micropipes in crystals grown on micropipe free/reduced seeds is correlated with second-phase formation, especially with the occurrence of C inclusions. Stress and micropipe densities are found to depend on the axial temperature gradients. Radial and axial temperature gradients were determined by the application of numerical modelling. Finally, the growth rate during PVT processing of SiC crystals was studied theoretically and experimentally. Both, a better control of vapor composition and a time-dependent variation of thermal boundary conditions are proposed for an augmentation of the crystallization rate. (C) 1999 Elsevier Science B.V. All rights reserved.