PHYSICAL VAPOR TRANSPORT GROWTH AND PROPERTIES OF SIC MONOCRYSTALS OF4H POLYTYPE

The physical vapor transport technique can be employed to fabricate la rge diameter silicon carbide crystals (up to 50 mm diameter) exhibitin g uniform 4H-polytype over the full crystal volume. Crystal growth rat e is controlled to first order by temperature conditions and ambient p ressure. 4H-polytype uniformity is controlled by polarity of the seed crystal and the growth temperature. 4H-SiC crystals exhibit crystallin e defects mainly in the form of dislocations with densities in the 10( 4) cm(-2) range and micropipe defects, the latter having densities as low as 10 cm(-2) in best crystals. Electrical conductivity in 4H-SiC b ulk crystals ranges from <10(-2) Omega cm, n-type, to insulating (>10( 15) Omega cm) at room temperature.