Reduction of Threading Screw Dislocation Density Utilizing Defect Conversion during Solution Growth of 4H-SiC

摘要

Reduction of threading screw dislocation density without polytype transformation from 4H-SiC was performed by the combination of step-flow growth and spiral growth. On a vicinal 4H-SiC seed crystal, threading screw dislocations are converted to Frank-type stacking faults by step-flow during solution growth. As the growth proceeds, the defects are excluded from the crystal. Thus utilizing the conversion, high quality SiC crystal growth without threading screw dislocations is expected to achieve. However, at the same time, polytype transformation was caused by the occurrence of 2D nucleation. By using the special shape of seed crystal, we successfully grew high quality 4H-SiC crystal without threading screw dislocation and polytype transformation.