Deformation-induced dislocations in 15R-SiC grown by sublimation

Single-crystal 15R-SiC boules have been successfully grown by sublimation. The Vickers hardness of a Si-terminated (0001) face has been measured in the temperature range 25-1300 degreesC. As expected, the hardness decreases with increasing temperature from about 30 GPa at room temperature to about 10 GPa at 1300 degreesC. The fracture toughness is estimated to be about 1.0 MPa m(1/2) at room temperature. Transmission electron microscopy investigation of the dislocations introduced by indentation at 900 and 1300 degreesC shows that they are activated predominantly on the basal plane. Most of them consist of a single leading partial without the corresponding trailing partial.