High-Accuracy Lattice Constant Measurements of Electron-Irradiated 6H-SiC Single Crystals

6H-SiC single crystals have been irradiated with 3 MeV electrons at a temperature of 200 K creating mainly vacancies on the carbon and the silicon sublattices. Positron annihilation experiments show that only well defined point defects have appeared. The influence of electron irradiation and of subsequent annealing on the lattice constants was studied by x-ray diffraction. An increase of the lattice constants by a relative value of 6DT10-5 due to the irradiation with a fluence of 1.8DT1019 cm-2 was observed. Annealing at 1000DGC in Ar atmosphere leads to a regain of the pre-irradiation values. Furthermore, the spread of lattice parameters present in the as-grown samples is reduced after irradiation and annealing. Higher annealing temperatures up to 1850DGC do not lead to further changes.