p-Type doping of SiC by high dose Al implantation—problems and progress

The development of optimized processes for p-type doping of SiC by ion implantation and subsequent annealing is a remaining challenge to SiC-device technology. Al is a promising acceptor in SiC. Compared to B it has a shallower acceptor level and a stronger tendency to occupy atomic sites in the Si sublattice which makes Al more suitable for the production of heavily doped, low resistivity layers. However, also in the case of Al very high acceptor concentrations (>1019 cm−3) are necessary to obtain SiC layers with low resistivities (<1 Ω cm). The physical consequences of such high impurity concentrations in SiC for the annealing of implantation damage and the electrical activation will be discussed. A survey of the results of several implantation and annealing schemes is presented.