Experimental verification of the model for formation of double Shockley stacking faults in highly doped regions of PVT-grown 4H-SiC wafers

We recently reported on the formation of overlapping rhombus-shaped stacking faults from scratches left over by the chemical mechanical polishing during high temperature annealing of PVT-grown 4H-SiC wafer. These stacking faults are restricted to regions with high N-doped areas of the wafer. The type of these stacking faults were determined to be Shockley stacking faults by analyzing the behavior of their area contrast using synchrotron white beam X-ray topography studies. A model has been proposed to explain the formation mechanism of the rhombus shaped stacking faults based on double Shockley fault nucleation and propagation. In this paper, we have experimentally verified this model by characterizing the configuration of the bounding partials of the stacking faults on both surfaces using synchrotron topography in back reflection geometry. As predicted by the model, on both the Si and C faces, the leading partials bounding the rhombus-shaped stacking faults are 30° Si-core and the trailing partials are 30° C-core. Using high resolution transmission electron microscopy, we have verified that the enclosed stacking fault is a double Shockley type.