Predictive models for co-doping effects between combinations of donors (P/As/Sb) and acceptors (B/Ga/In)

We studied co-doping effects in silicon using first principles calculations, with particular attention to charge compensation, Coulomb interactions and strain compensation. We find that for B-doped systems, As or Sb counter-doping reduces the hole concentration, but that due to strong binding of multiple P atoms, Ga or In counter-doping can increase electron density in P doped material. For acceptor-acceptor pairing, we find the B-B interaction to be repulsive as expected due to Coulombic effects, but calculations show a surprisingly strong attractive binding between B and In, which we attribute to hole localization. However, B-In binding is not promising for enhancing hole concentration since BIn pairs are deep acceptors. Both donor-acceptor and acceptor-acceptor pairing can be helpful in reducing dopant diffusion leading to more abrupt junctions