Electron-irradiation-induced deep levels in n-type 6H-SiC

The fluence-dependent properties and the annealing behavior of electron-irradiation-induced deep levels in n-type 6H-SiC have been studied using deep-level transient spectroscopy (DLTS). Sample annealing reveals that the dominant DLTS signal at E-C-0.36 eV (labeled as E1 by others) consists of two overlapping deep levels (labeled as ED3L and ED3H). The breakup temperature of the defect ED3L is about 700 degrees C. The ED3H center together with another deep level located at E-C-0.44 eV (so-called E2) can withstand high-temperature annealing up to 1600 degrees C. It is argued that the involvement of the defect ED3L is the reason that various concentration ratios of E1/E2 were observed in the previous work. The revised value of the capture cross section of the deep-level ED3H has been measured after removing ED3L by annealing. A deep level found at E-C-0.50 eV is identified as a vacancy-impurity complex since it was found to have a lower saturated concentration and weak thermal stability. Two other deep levels, E-C-0.27 eV and E-C-0.32 eV, which were not observed by others because of the carrier freeze-out effect, are also reported. (C) 1999 American Institute of Physics. [S0021-8979(99)07911-6].