In SiC vapor growth, micro-pipes and dislocations that originate at the seed/boule interface could continuously propagate into the newly grown crystal and adversely affect the quality of the crystals. The defect density could be reduced by the method of growing a large diameter crystal from a small seed through lateral growth under controlled thermal environment. Here, SiC growth processes with varying thermal conditions were simulated; the shapes of the as-grown crystals were predicted and the thermo-elastic stress fields in the crystals were calculated to describe the dislocation density distributions. The simulation results show that if thermal conditions were properly controlled, it was possible to reduce the micro-pipe density through lateral growth without increasing basal plane dislocation density. The effects of operational parameters such as the axial and radial temperature gradients and seed mounting technique on the size and quality of the crystals were also investigated. The ceramic polycrystalline material that grows on the crystal periphery was illustrated to jeopardize the quality of the crystals. In addition, the influences of some geometrical parameters on thermal environments in the growth chamber were also analyzed. The current finding could also help in the design of AlN/GaN growth system.

Thermal System Design and Dislocation Reduction for Growth of Wide Band Gap Crystals - Application to SiC Growth. R.H.Ma, H.Zhang, M.Dudley, V.Prasad: Journal of Crystal Growth, 2003, 258[3-4], 318-30