Study on the elastoplastic deformation behavior and dislocation evolution of 4H-SiC film

The elastoplastic deformation behavior and dislocation evolution of 4H-SiC film are systematically investigated by molecular dynamics simulation of nanoindentation and the generalized stacking fault energy (GSFE) analysis. It is found that "pop-in" event occur in the process of the film deformation, which is the critical point for the elastic-plastic transition of the film. At lower load, to release the deformation energy and shear stress within the film, the film undergoes elastic deformation along the direction of easy deformation. As the load continues to increase, the film shifts to plastic deformation. The dislocations in the plastic deformation region are mainly full dislocations, and the deformation is dominated by the propagation of full dislocations as the depth increases. Partial dislocations are more likely to be nucleated at deeper depth. The GSFE analysis reveals that the film, after being subjected to external load, preferentially activates the dislocation with a Burgers vector of 1/31120. The dislocation is then dissociated into two partial dislocations, namely leading and trailing partial dislocations. Meanwhile, the slip of 1/31100 dislocation can also occur on the base plane.