Factors affecting the graphitization behavior of the powder source during seeded sublimation growth of SiC bulk crystal

The effects of temperature, temperature gradient and the argon pressure on the graphitization of the powder source during seeded sublimation growth of SiC bulk crystal are investigated. It is found that the graphitization tendency of the powder source becomes obvious with temperature, especially above 2600 K. A higher growth temperature, a larger temperature gradient from the powder source to the growing crystal or a lower argon pressure corresponds to a higher graphitization rate of the powder source. The establishment of a proper temperature gradient in the powder source enabling vapor transporting from the lower part of the powder to the surface is critical to prevent the graphitization of the powder surface. This requires a proper control of the distance between the powder surface and the highest temperature line in the furnace during growth. (C) 2003 Elsevier B.V. All rights reserved.