LARGE-DIAMETER 6H-SIC FOR MICROWAVE DEVICE APPLICATIONS

6H-polytype SiC single crystals with diameters up to 50 mm and lengths up to 75 mm have been grown in the c-and a-axis directions by physica l vapor transport (PVT) at growth rates of 0.25 to 1 mm h-1. Undoped c rystals grown from purified source material reveal residual impurity c oncentrations in the 10(16) cm-3 range and resistivities up to 1000 OM EGA . cm. N+ crystals with resistivities < 0.02 OMEGA . cm have been p roduced bv controlled nitrogen doping. PVT-grown SiC crystals are char acterized by dislocation densities of 10(4) to 10(5) cm-2 and can also exhibit micropipe defects in the 10(2) to 10(3) cm-2 range.