It was noted that the EI5 and EI6 centers were typical intrinsic defects in radiation-damaged and semi-insulating 4H-SiC. Their origins had been attributed to positively charged C vacancies (VC+) and Si antisites (SiC+), respectively. However, a complete set of 29Si hyperfine data clearly revealed that both centers should originate from VC+, but their locations were different: quasi-cubic sites for EI5 and hexagonal sites for EI6, as predicted by first-principles calculations. The 2 types of VC+ center exhibited remarkable differences in their atomic structures, as well as in the temperature dependence of the hyperfine interactions; which were closely related to the natures of the 2 sites.

EPR Identification of Two Types of Carbon Vacancies in 4H-SiC. T.Umeda, J.Isoya, N.Morishita, T.Ohshima, T.Kamiya: Physical Review B, 2004, 69[12], 121201 (4pp)