Micropipes and the closure of axial screw dislocation cores in silicon carbide crystals

The micropipes in 6H, 4H, and 15R-SiC semiconductor wafer were discussed using scanning electron microscopy. It was found that the screw dislocations intersecting wafers surfaces were located by etch pitting and their Burgers vector were determined. It was observed that in case of 6H-SiC, hollow cores were never observed at the base of the craters. Analysis shows that screw dislocations in 15R-SiC crystals had hollow cores.