A thermal admittance spectroscopic investigation was made of the effect of sequential C and B co-implantation upon B-related acceptors and deep levels in 4H-type material. The density of deep levels decreased upon increasing the concentration of co-implanted C, and was completely suppressed at a C/B ratio of 1:1. The densities and ionization energies of B acceptors increased and decreased, respectively, with increasing C concentration. It was found that excess C led to the formation of a complex defect. Capacitance-voltage results also indicated an increase in the free hole concentration with increasing concentration of the co-implanted C atoms. This was followed by a decrease in the concentration under C-rich conditions. The results were in reasonable agreement with the behavior of B acceptors and deep-defect levels. The concentration of co-implanted C atoms was considered to be very sensitive to the formation of B acceptor levels.

Effect of C and B Sequential Implantation on the B Acceptors in 4H-SiC. Y.Nakano, R.K.Malhan, T.Kachi, H.Tadano: Journal of Applied Physics, 2001, 89[11], 5961-4