Some like it shallower -: p-type doping in SiC

The usual p-type dopants of SiC, B, and Al, do not produce really shallow levels. In fact, boron can give rise to a secondary very deep acceptor level as well. The picture is complicated by hydrogen which is readily incorporated during in-growth doping into p-type material and can passivate both dopants but to a different degree. First principle calculations are reported regarding the interaction of hydrogen with B and Al in SiC. The results explain why hydrogen is incorporated in much higher amounts into B-doped than into Al-doped samples, and also reveal the influences of hydrogen on boron to produce the shallower acceptor. It will be shown that hydrogen incorporation during growth does not influence Al. Finally an Al-N-Al complex is proposed as a shallower acceptor in SiC.