Doping of 4H-SiC with Group IV Elements
Germanium (Ge) doping of 4H silicon carbide (SiC) has recently attracted attention because a conductivity-enhancing effect was reported. In this work, we report on an experimental and theoretical approach to elucidate this effect. Ge and tin (Sn) – a second candidate of group IV elements – have been implanted into n-type 4H-SiC. Despite the expected isoelectric nature of Ge and Sn, a more efficient annealing of implantation-induced defects was observed compared to noble gas implantation with identical simulated initial implantation damage. In particular, a strong reduction of the prominent Z1/2 defect was observed. Density functional theory calculations under equilibrium conditions show that Ge is mainly incorporated on a substitutional silicon lattice site without creating new charge transition levels in the bandgap. The low abundance of other Ge-related defects suggests that kinetic mechanisms should be responsible for the observed effect of group IV doping.
Fabrizio Roccaforte, Francesco La Via, Roberta Nipoti, Danilo Crippa, Filippo Giannazzo and Mario Saggio
M. Krieger et al., "Doping of 4H-SiC with Group IV Elements", Materials Science Forum, Vol. 858, pp. 301-307, 2016