"Structural features and electronic properties of group-III, group-IV, and group-V-doped Si nanocrystallites",
L.E. Ramos, E. Degoli, G. Cantelle, S. Ossicini, D. Ninno,J. Furthmüller, and F. Bechstedt,
J. Phys. C: Condens. Matt. 19 , 466211 (2007).

We investigate the incorporation of group-III (B and Al), group-IV (C and Ge), and group-V (N and P) impurities in Si nanocrystallites. The structural features and electronic properties of doped Si nanocrystallites, which are faceted or spherical-like, are studied by means of an ab initio pseudopotential method including spin polarization. Jahn-Teller distortions occur in the neighborhood of the impurity sites and the bond lengths show a dependence on size and shape of the nanocrystallites. We find that the acceptor (group-III) and donor (group-V) levels become deep as the nanocrystallites become small. The energy difference between the spin-up and spin-down level of group-III and group-V impurities decreases as the size of the Si nanocrystallite increases and tends to the values calculated for Si bulk. Doping with carbon introduces and impurity-related level in the energy gap of the Si nanocrystallites.