Variation in lattice parameters of 6H-SiC irradiated to extremely low doses

Irradiation of 6H-SiC single crystals was performed using 4 MeV H+ ions at 340 and 210 K. The changes in lattice parameters in the basal plane and along the c axes were measured as a function of dose using high-resolution x-ray diffraction. The c-axis lattice parameter increases monotonically with the increasing dose, while a-axis lattice parameter decreases at extremely low doses. An initial volumetric contraction of the unit cell is observed. The decrease in the a parameter may originate from the irradiation-induced vacancies and the possible formation of antisite defects that cause the lattice structure on the basal plane to shrink