New Insights into the Occurrence of Prismatic Slip During PVT Growth of SiC Crystals

Prismatic slip systems are the secondary slip systems in Silicon carbide (4H-SiC) crystals. The previously proposed radial thermal model of the PVT growth process for SiC crystals, which predicts the occurrence of slip in different prismatic planes as a function of the radial position in the boule, has been shown to generally work well. Recent observations of growth interface nucleation of prismatic slip necessitated updating the thermal model to incorporate the effects of the curvature of the growth interface. A 3D finite element model has been developed to include the growth interface curvature complexity. The model predicts high dislocation densities due to prismatic slip near the peripheral regions dropping to zero near the center for wafers from sections of the boule grown with a flatter interface and a less dense distribution of prismatic slip dislocations that extends to the center for wafers from boule sections grown with a more convex interface. Additionally, due to such an interface-initiated prismatic slip,, the asymmetrical step configuration produced by off-axis growth results in an asymmetrical distribution of prismatic slip. The studies suggest that a reduced surface curvature is necessary to suppress the prevalence of interface-related prismatic slip generation.