In Situ Study of Low-Temperature Irradiation-Induced Defects in Silicon Carbide

Ni/4H-SiC Schottky barrier diodes have been irradiated by 5.4-MeV helium ions at cryogenic temperatures and their electrical characteristics investigated. Only the prominent native defects (E0.11, E0.16, and E0.65) were observed before and after low-temperature irradiation at 50 K, with a baseline on the spectrum observed starting at 190 K. Low-temperature irradiation reduced the concentration of native E0.11 and E0.16 defects. After annealing at 380 K, E0.37, E0.58, E0.62, E0.73, and E0.92 defects were observed. These results show that E0.62, an acceptor level of the Z1 center, and E0.73, an acceptor level of the Z2 center, are both secondary defects which are not formed directly from the irradiation process but from succeeding thermal reactions. An interpretation of the formation of the secondary defects is given.