Band gap states of Ti, V, and Cr in 4H–silicon carbide

Band gap states of Ti, V, and Cr in n-type 4H–SiC were investigated by radiotracer deep level transient spectroscopy (DLTS). Doping with the radioactive isotopes V48 and Cr51 was done by recoil implantation followed by annealing (1600 K). Repeated DLTS measurements during the elemental transmutation of these isotopes to Ti48 and V51, respectively, reveal the corresponding concentration changes of band gap states. Thus, six levels are identified in the band gap: Cr levels at 0.15, 0.18, and 0.74 eV, one V level at 0.97 eV, and two Ti levels at 0.13 and 0.17 eV below the conduction band edge.