Anisotropic deformation of 4H-SiC wafers: insights from nanoindentation tests

In this work, the anisotropic deformation and anisotropic mechanical properties of 4H silicon carbide (4H-SiC) single crystal wafers are proposed by using nanoindentation. The C face of a 4H-SiC wafer has higher hardness and lower fracture toughness than those of the Si face. Because the deformation of 4H-SiC is assisted by the nucleation and slip of basal plane dislocations (BPDs), especially the slip of Si-core partial dislocations (PDs) of the BPDs, the nucleation and slip of the Si-core PDs in the Si face of 4H-SiC is easier than those in the C face, which releases the nanoindentation-induced stress and results in the decrease of the hardness and increase of the fracture toughness of the Si face of 4H-SiC wafers. Due to the hexagonal lattice of 4H-SiC, the hardness along < 1<(1)over bar>00 > of 4H-SiC is higher than that along < 11<(2)over bar>0 >, but the fracture toughness along the < 1<(1)over bar>00 > is lower than that along the < 11<(2)over bar>0 >, as a result of the enhanced glide of dislocations along the most closely-packed direction. The insights gained in this work are expected to shed light on the optimization of the mechanical processing of 4H-SiC wafers.

Automated summary

Anisotropic deformation and mechanical properties of 4H silicon carbide (4H-SiC) single crystal wafers were investigated using nanoindentation. The C face of the wafer exhibited higher hardness and lower fracture toughness compared to the Si face. The deformation mechanism was found to be assisted by the nucleation and slip of basal plane dislocations (BPDs) and the nucleation and slip of Si-core partial dislocations (PDs) in the Si face were easier than in the C face, leading to changes in the hardness and fracture toughness of the Si face. The insights gained from this study are expected to be valuable for optimizing the mechanical processing of 4H-SiC wafers.