Characterization of the three-dimensional residual stress distribution in SiC bulk crystals by neutron diffraction

Abstract

Characterization of residual stress in bulk crystals is of vital importance since it can provide abundant information on the crystal growth and process techniques. In this paper, the residual stress in 4H-SiC bulk crystals was investigated by neutron diffraction. Detailed strain and stress calculations were performed using the Bragg equation and Hooke's law. The (0004), (11−20) and (1−100) plane diffraction profiles were measured. The strain and stress in three directions were found to be on the order of 10⁻⁴–10⁻³ and 100–1000 MPa, respectively. Moreover, the stress distributions in different directions were anisotropic. Amongst the stresses in these three directions, the stresses in the <1−100> direction were tensile and the maximum value was up to 2953 MPa, which indicated that there was a high risk of the grown crystals cracking in this direction.