Structure and electronic properties of Si/SiO clusters, nanoparticles and nanowires

Avramov, P.; Kuzubov, A. A.*; Fedorov, A. A.*; Tomilin, F. N.*; Sorokin, P. B.*

The small SiO clusters are the precursors of the Si/SiO objects and play a key role in their synthesis. The reaction paths for formation and isomerization of a set of silica SiO (m=2, 3, n=1-5) nanoclusters have been investigated using second order pertubation theory (MP2) with the 6-31G(d) basis set. Although transition states have been located for many isomerization reactions, only for SiO and SiO some transition states have been found for the formation of a cluster from the separated reactants. The electronic structure calculations of the Si and Si/SiO quantum dots and nanowires have been performed using the DFT B3LYP/6-31G and PBC LDA PP PW approximations. The polycrystalline nature of the Si nanowires and Si quantum dots leads to the metallic state of all species. The oxidized SiO surface leads to stabilization of the atomic structure of all Si/SiO nanowires and to the opening of the semiconductor gap (1.4eV) in the TDOS. The top of the valence band and the bottom of the conductivity band of the Si/SiO nanoobjects are formed manly by Si p-states.