Basal plane dislocation reduction in 4H-SiC epitaxy by growth interruptions

The paths of basal plane dislocations (BPDs) through 4H-SiC epitaxial layers grown on wafers with an 8 degrees offcut were tracked using ultraviolet photoluminescence imaging. The reduction of BPDs by conversion to threading edge dislocations was investigated at ex situ and in situ growth interrupts. For ex situ interrupts, BPDs are imaged after each of several growths. The wafer remains in the reactor for in situ interrupts and BPDs are imaged after the growth is finished. For in situ interrupts, a combination of temperature, propane flow, and duration has been determined, which achieve a BPD reduction of 98%.