Electron paramagnetic resonance study on n-type electron-irradiated 3C-SiC

Electron Paramagnetic Resonance (EPR) was used to study defects in n-type 3C-SiC films irradiated by 3-MeV electrons at room temperature with a dose of 2×1018 cm-2. After electron irradiation, two new EPR spectra with an effective spin S = 1, labeled L5 and L6, were observed. The L5 center has C3v symmetry with g = 2.004 and a fine-structure parameter D = 436.5×10-4 cm-1. The L5 spectrum was only detected under light illumination and it could not be detected after annealing at ~550°C. The principal z-axis of the D tensor is parallel to the -directions, indicating the location of spins along the Si-C bonds. Judging from the symmetry and the fact that the signal was detected under illumination in n-type material, the L5 center may be related to the divacancy in the neutral charge state. The L6 center has a C2v-symmetry with an isotropic g-value of g = 2.003 and the fine structure parameters D = 547.7×10-4 cm-1 and E = 56.2×10-4 cm-1. The L6 center disappeared after annealing at a rather low temperature (~200°C), which is substantially lower than the known annealing temperatures for vacancy-related defects in 3C-SiC. This highly mobile defect may be related to carbon interstitials