Positron lifetime studies on 8 MeV electron-irradiated n-type 6H silicon carbide

The positron lifetime technique was employed to study vacancy-type defects in 8MeV electron-irradiated n-type 6H silicon carbide. A long-lifetime component having a characteristic lifetime of 223-232 ps was observed in the irradiated sample and was attributed to the V cV Si divacancy. Other positron traps, which dominated at low temperatures, were observed to compete with the V cV Si for trapping positrons. A positron trapping model involving a positron shallow trap, a negatively charged monovacancy and the V cV Si divacancy was found to give a good description of the temperature-dependent positron lifetime data of the 1200 °C annealed sample. The identity of the monovacancy could not be unambiguously determined, but its lifetime was found to be in the range 160-172ps.