Method of producing silicon-carbide single crystals by sublimation

Abstract

There is provided a method of producing a high-quality n-type, 6H silicon carbide single crystal with good reproducibility. A silicon carbide single crystal substrate having a growth orientation of <0001>, as a seed crystal, is mounted to an inner surface of a cover of a graphite crucible. A source material includes a high-purity silicon carbide powder having an impurity proportion of not more than 1 ppm and an aluminum powder of 50 ppm relative to the silicon carbide powder. The source material is loaded into the graphite crucible. The graphite crucible is closed with a seed crystal-mounted cover placed in a double quartz tube. Ar gas and N.sub.2 gas are caused to flow in the double quartz tube. Temperature of the silicon carbide powder and aluminum powder is controlled to 2300.degree. C., and temperature of the silicon carbide single crystal substrate to 2200.degree. C.; and interior of the double quartz tube is controlled to 30 torr. Silicon carbide single crystal growth is effected on the seed crystal under these conditions. A high-quality n-type, 6H silicon carbide single crystal is thus obtained which has a uniform crystal structure with little defect, if any, throughout its structure, from the substrate surface to the outermost grown surface, and has a specific resistance of 0.5 .OMEGA.cm.