Surface-phosphorus interaction in Si nanocrystals

Abstract

The properties of phosphorus-related defects in freestanding silicon nanocrystals with different surface compositions are investigated using density functional theory models. Both hydrogen (H-) and hydroxyl (OH-) covered surfaces are considered. The dependence of the formation energy of substitutional phosphorus on the distance to the surface is found to be stronger in hydroxyl-covered crystals. The formation of tricoordinated defects, energetically favourable in hydrogenated nanocrystals, is less likely in nanocrystals with hydroxylated surfaces. Further, the ionisation energy level of P-doped nanocrystals is found to be deeper in OH-covered nanocrystals than in H-covered nanocrystals. © Published under licence by IOP Publishing Ltd 2011.