THE GROWTH-CHARACTERISTICS OF CHEMICAL-VAPOR-DEPOSITED BETA-SIC ON A GRAPHITE SUBSTRATE BY THE SICL4/C3H8/H-2 SYSTEM

Silicon carbide has been grown at 1300-1800 degrees C by chemical vapour deposition using the SiCl4/C3H8/H-2 system on a graphite substrate. The effect of C3H8 flow rate and deposition temperature on the growth characteristics and structure of the deposit has been studied. The experimental results show that the degree of film density is changeable from a dense plate to a porous one with increasing C3H8 flow rate. The activation energy increases with increasing C3H8 flow rate. The grain size of the polycrystalline beta-SiC becomes coarser when the C3H8 flow rate and the deposition temperature are increased. The preferred orientation of the deposited SiC layers changes from (111) to (220) on increasing deposition temperature from 1300 degrees C to 1400 degrees C. The deposition mechanism is also discussed.