Nucleation of threading dislocations in sublimation grown silicon carbide

The structural defects in sublimation-grown silicon carbide layers have been investigated by transmission electron microscopy, atomic force microscopy, x-ray topography, and KOH etching. Nucleation of two-dimensional islands on damage free surfaces of high quality Lely seeds led to formation of stacking faults at the initial stages of growth. The location and number of stacking faults correlates with threading dislocation density. Also, the growth rate is shown to have a pronounced effect on the threading dislocation densities. Elementary screw dislocation density has been observed to increase from 20cm ^-2 to 4×10 ³cm ^-2 for growth rates increasing from 0.02 to 1.5 mm/h. Growth on seeds miscut 5° off the c axis resulted in screw dislocation densities almost two orders of magnitude lower than on axis growth. The results are interpreted as due to SiC stacking disorder at the initial stages of growth.