Electronic energy model for single Shockley stacking fault formation in 4H-SiC crystals

The expansion/contraction behavior of single Shockley-type stacking faults (1SSFs) in 4H-SiC crystals is investigated by using an electronic energy model. The model takes into account several factors that were not considered in the previous models and provides a guideline to understand the 1SSF behavior. The authors calculated the threshold excess carrier density, which is the critical excess carrier density for the expansion/contraction of a 1SSF, for two models: with and without carrier recombination at a 1SSF. In the case of the model without carrier recombination, the obtained threshold excess carrier density at room temperature was at least 1x1017cm-3. On the other hand, the threshold excess carrier density at room temperature given by the model with carrier recombination was in the range of 2x1014 to 2x1016cm-3, which shows good agreement with the previous experimental results quantitatively. The authors also discuss the temperature-, doping-concentration-, and conduction-type-dependences of the threshold excess carrier density. The calculated doping-concentration- and conduction-type-dependences of the threshold excess carrier density imply that the 1SSF expansion easily occurs in the heavily-doped crystals, and n-type 4H-SiC is slightly less tolerant against bipolar degradation than the p-type one.