Doping of Si nanoparticles: the effect of oxidation
  The preferred location of boron and phosphorus in oxidized free-standing Si nanoparticles was investigated using a first-principles density functional approach. The calculated formation energies indicate that P should segregate to the silicon core, whereas B is equally stable in the Si and SiO_2 regions. Our models thus suggest that, in contrast with nanocrystals with H-terminated surfaces, the efficiency of phosphorus incorporation in oxidized Si nanoparticles can be improved by thermal annealing. 
A. Carvalho, S. Oberg, M. Barroso, M. J. Rayson and P. R. Briddon
cond-mat.mtrl-sci cond-mat.mes-hall