Calculations of codoping effects between combinations of donors (P/As/Sb) and acceptors (B/Ga/In) in Si

We studied codoping 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 maximum hole concentration, but that due to strong binding of multiple P atoms, Ga or In counter doping can increase electron density in heavily 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 significant 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. (c) 2007 American Institute of Physics.