Changes in thermal conductivity and bandgap of SiC single crystals in accordance with thermal stress

Thermal stress according to growth temperature and surface region of single crystal SiC was analyzed using ABAQUS simulation. Three 6H SiC single crystal wafers grown with the PVT method under the same growth conditions by different companies were used to analyze the changes in properties caused by thermal stress. All three wafers differed in diffraction distance. The wafer with the higher tensile stress from thermal stress showed a larger diffraction distance. Also the impact of thermal stress on crystallinity and defect density was analyzed. Our results showed that the wafer with the higher thermal stress had lower crystallinity and more defects, and we also confirmed that the wafer had a lower thermal conductivity and bandgap.

► Thermal stress increased as temperature was raised and the center of the crystal received higher thermal stress than the edge.
► The 6H SiC single crystal wafer with higher tensile stress from thermal stress showed farther diffraction distance.
► The 6H SiC single crystal wafer with higher thermal stress showed lower crystallinity and more defects.
► The 6H SiC single crystal wafer with higher thermal stress had lower thermal conductivity and bandgap.