Esr in irradiated silicon carbide

Thirty samples of n- and p-type 6H and n-type 3C silicon carbide single crystals were irradiated at room temperature with either 0.8 or 1.0 MeV electrons or reactor neutrons. Seven different radiation- induced e.s.r. spectra were found. Some of these have been described before, but further investigations of production rates and annealing behaviour have necessitated changes in the previously proposed models. The e.s.r. parameters of these centres are given. Three of the spectra are tentatively ascribed to (1) the uncharged carbon vacancy, (2) the negatively charged carbon divacancy, and (3) the uncharged silicon vacancy trapped at a boron site. Tentative models for three other centres are discussed.