Micropipe free c-plane 4H-SiC wafers were achieved by sublimation growth on the 4H-SiC {0338} seed. 4H-SiC {0338} seeds were obtained by inclining the c-plane to < 0110 > at 54.7 degrees. A transmission X-ray topograph of the micropipe free c-plane wafer revealed that there were no macroscopic defects with lattice displacements. Crystal growth of undoped (vanadium-free) semi-insulating 6H-SiC was carried out by our sublimation system. In order to achieve high resistivity, high-purity SiC source and controlled instruments were used for the reduction of nitrogen, boron and metal impurity backgrounds. Hence high-purity and high-resistivity 6H-SiC 2 and 3 in in diameter were developed for high-frequency power transistors. (c) 2006 Elsevier B.V. All rights reserved.