Doping of 4H-SiC with Group IV Elements

Abstract

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.