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 $E_C\text{−0.36\hspace{0.05em}}\mathrm{eV}$ (labeled as $\text{E1}$ by others) consists of two overlapping deep levels (labeled as ${\mathrm{ED}}_{\text{3L}}$ and ${\mathrm{ED}}_{\text{3H}}\mathrm{).}$ The breakup temperature of the defect ${\mathrm{ED}}_{\text{3L}}$ is about 700 °C. The ${\mathrm{ED}}_{\text{3H}}$ center together with another deep level located at $E_C\text{−0.44\hspace{0.05em}}\mathrm{eV}$ (so-called $\text{E2)}$ can withstand high-temperature annealing up to 1600 °C. It is argued that the involvement of the defect ${\mathrm{ED}}_{\text{3L}}$ is the reason that various concentration ratios of $\text{E1/E2}$ were observed in the previous work. The revised value of the capture cross section of the deep-level ${\mathrm{ED}}_{\text{3H}}$ has been measured after removing ${\mathrm{ED}}_{\text{3L}}$ by annealing. A deep level found at $E_C\text{−0.50\hspace{0.05em}}\mathrm{eV}$ 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, $E_C\text{−0.27\hspace{0.05em}}\mathrm{eV}$ and $E_C\text{−0.32\hspace{0.05em}}\mathrm{eV},$ which were not observed by others because of the carrier freeze-out effect, are also reported.