First-principles theoretical analysis of dopant adsorption and diffusion on surfaces of ZnSe nanocrystals

We report results from a detailed analysis of dopant adsorption and diffusion on surfaces of ZnSe nanocrystals and discuss their implications for dopant incorporation into the growing nanocrystals. Using first-principles density functional theory calculations, we find that the binding energy for Mn dopant adsorption onto various surface sites of the dominant dopable surface, ZnSe(001)-(2 x 1), increases with increasing dopant surface concentration. Due to low activation barriers, dopant atoms can migrate fast along the Se dimer rows without substantial surface relaxation, while their diffusion across the dimer rows is governed by a high-barrier pathway. (C) 2008 Elsevier B.V. All rights reserved.