Identities of the deep level defects E 1/E 2 in 6H silicon carbide

Abstract

E 1/E 2 (Ec-0.36/0.44eV) are deep level donors generally found in ion-implanted, electron and neutron irradiated n-type 6H-SiC materials, Their configurations are controversial and have been related to a negatively charged carbon vacancy, a divacancy or a V si-complex . With positron lifetime technique, we have identified V si and V cV si in the Lely grown n-type 6H-SiC sample, with V si annealed out at 650°C. Concentration of V cV si persists at 1400°C annealing and significantly decreased after the 1600°C annealing. Considering the deep level transient spectroscopic (DLTS) results on the neutron irradiated n-type SiC epi sample that E 1/E 2 completely disappeared after the 1400°C annealing, E 1/E 2 is not the V cV Si defect. With positron annihilation techniques, Rempel et al [1] have shown the energy dependence of vacancy generated by electron irradiation. With low irradiation energy of 0.3MeV, only V c was generated and at higher energy (0.5MeV), Si vacancy was detected. With focus to find the minimum energy for generating E 1/E 2, we have performed DLTS studies on n-type epi 6H-SiC materials irradiated by electrons with varying energies. Our results suggest that E 1/E 2 have microstructure related to a carbon vacancy or a carbon interstitial.