Computational study of anisotropic epitaxial recrystallization in 4H-SiC

Abstract

Two nano-sized amorphous layers were created within a crystalline cell to study anisotropicexpitaxial recrystallization using molecular dynamics (MD) methods in 4H-SiC. Bothamorphous layers were created with the normal of the amorphous–crystalline (a–c)interfaces along the [0001] direction, but one had a microscopic extension along the [] direction, i.e. the dimension along the [] direction is much larger than that along the [] direction (Ix model), and the other had a microscopic extension along the [] direction (Iy model). The amorphous layer within theIx model can be completely recrystallized at 2000 K within an achievable simulation time, and therecrystallization is driven by a step-regrowth mechanism. On the other hand, the nucleationand growth of secondary ordered phases are observed at high temperatures in theIy model. The temperature for recrystallization of the amorphous layer into high-quality4H-SiC is estimated to be below 1500 K. Compared with other models, it is found that theregrowth rates and recrystallization mechanisms depend strongly on the orientation of4H-SiC, whereas the activation energy spectra for recrystallization processes areindependent of any specific polytypic structure, with activation energies ranging from 0.8 to1.7 eV.