Physical vapor transport growth and properties of SiC monocrystals of 4H polytype

Abstract

The physical vapor transport technique can be employed to fabricate large diameter silicon carbide crystals (up to 50 mm diameter) exhibiting uniform 4H-polytype over the full crystal volume. Crystal growth rate is controlled to first order by temperature conditions and ambient pressure. 4H-polytype uniformity is controlled by polarity of the seed crystal and the growth temperature. 4H-SiC crystals exhibit crystalline defects mainly in the form of dislocations with densities in the 104 cm-2 range and micropipe defects, the latter having densities as low as 10 cm-2 in best crystals. Electrical conductivity in 4H-SiC bulk crystals ranges from <10-2 Ω cm, n-type, to insulating (>1015 Ω cm) at room temperature.