Origin of basal plane bending in hexagonal silicon carbide single crystals

4H-SiC crystals grown by the physical vapor transport method were investigated using high-resolution X-ray diffraction, defect selective etching, and transmission electron microscopy. The (0 0 0 8) diffraction peak position shifted about 2.5° along the 3 in crystal diameter indicating the bending of the basal plane. Transmission electron microscopy revealed that the basal plane bending is due to plastic-deformation-induced basal plane dislocations with at least a partial edge character. The dislocations had a non-zero net Burgers vector with the net extra half-plane pointing toward the seed side of the crystal, and thus, caused the basal plane to bend concave toward the growth direction. The plastic deformation is suggested to be due to thermoelastic shear stresses imposed on the crystal during the physical vapor transport (PVT) growth.