Room-temperature yield and fracture strength of single-crystalline 6H silicon carbide

摘要

Silicon carbide (SiC) has excellent physical and electrical properties with potential for nuclear applications and power semiconductors. The properties of SiC, however, have not been fully determined. One property in question is the critical resolved shear stress (CRSS) for slip at room temperature. Here we evaluated the CRSS of 6H-SiC using micro-compression tests. Single-crystalline micro-pillars were fabricated on the surface of a 6H-SiC(0001) wafer. Brittle fracture occurred in all the fabricated micro-pillars. The compressive fracture strength of the material was determined to be near 24 GPa. Micro-pillars were also fabricated on a tilted specimen, to facilitate slip on the basal plane of hexagonal close-packed structure. Plastic deformation was observed in micro-pillars below 0.49 mu m in diameter. Cross-sectional TEM observation of the compressed micro-pillars showed clear slip traces and dislocations on the basal {0001} planes. The CRSS of 6H-SiC was determined to be 9.8 +/- A 0.69 GPa from the measured stress-strain curves and the sample geometry. The CRSS evaluated here was compared with that determined from first-principle calculations reported in the literature.