title: Excitonic and quasiparticle gaps in Si nanocrystals
abstract: We present calculations of the one- and two-particle excitations in silicon nanocrystals. The one-particle properties are handled in the GW approximation, and the excitonic gap is obtained from the Bethe-Salpeter equation. We develop a tight binding version of these methods to treat clusters up to 275 atoms. The self-energy and Coulomb corrections almost exactly cancel each other for crystallites with radius larger than 0.6 nm. The result of this cancellation is that one-particle calculations give quite accurate values for the excitonic gap of crystallites in the most studied range of sizes.
authors.affiliation: Institut d'Electronique et de Microelectronique du Nord, Departement Institut Superieur d'Electronique du Nord, 41 boulevard Vauban 59046 Lille Cedex, France.
authors.initials: C
authors.lastname: Delerue
authors.initials: M
authors.lastname: Lannoo
authors.initials: G
authors.lastname: Allan