Growth and Properties of Hexagonal SiC Bulk Crystals and Epilayers

Growth of bulk hexagonal SiC crystals by Physical Vapor Transport relies on sublimation / condensation of a solid SiC charge performed in a semi-closed crucible at 2200-2400 deg C. The gradual loss of silicon-rich vapor results in the shift of crystal stoichiometry from silicon to carbon rich and associated change of nitrogen dopants. The thermal gradients during growth induce stresses sometimes in excess of critical resolved shear stress reduced by high growth temperatures. This results in plastic deformation of the growing boules through the activation of ''(0001) slip system. SiC epitaxial layers are deposited by Chemical Vapor Deposition process performed at 1500-1700 deg C using silane and propane in hydrogen carrier gas. Since the polytype nucleating at these temperature is 3C-SiC, the layers are grown on off-cut substrates in step flow mode. Approaches to epitaxy producing layers suitable for high voltage power devices i.e. with low defect density ( < 1 cm-2), low doping (1X1015 cm-3), and long carrier lifetimes ( > 1 mus) are described.