Structure and stability of germanium nanoparticles - art. no. 165324

In order to tailor the properties of nanodots, it is essential to separate the effects of quantum confinement from those due to the surface, and to de termine the mechanisms by which preparation conditions can influence the pr operties of the dot. We address these issues for the case of small Ge clust ers (1-2.5 nm), using a combination of empirical and first-principles molec ular-dynamics techniques. Our results show that over a wide temperature ran ge, the diamond structure is more stable than tetragonal-like structures fo r clusters containing more than 40 atoms; however, the magnitude of the ene rgy difference is strongly dependent on the structure and termination of th e surface. On the basis of our calculations, we propose a possible mechanis m for the formation of metastable tetragonal clusters observed in vapor dep osition experiments, by cold quenching of amorphous nanoparticles exhibitin g unsaturated, reconstructed surfaces.