THE THEORETICAL DFT STUDY OF ELECTRONIC STRUCTURE OF THIN Si/SiO 2 QUANTUM NANODOTS AND NANOWIRES Pavel V. Avramov 1, 2 , Alexander A. Kuzubov 2 , Alexander S. Fedorov, 2 Pavel B. Sorokin 2, 3 , Felix N. Tomilin 2 and Yoshihito Maeda 1, 4 1 Takasaki-branch, Advanced Science Research Center, Japan Atomic Energy Agency, Takasaki, 370-1292, Japan 2 L.V. Kirensky Institute of Physics SB RAS, Academgorodok, 660036, Russia 3 N.M. Emanuel Institute of Biochemical Physics of RAS, 119334 Moscow, Russian Federation 4 Department of Energy Science and Technology, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan The atomic and electronic structure of a set of proposed thin (1.6 nm in diameter) silicon/silica quantum nanodots and nanowires with narrow interface, as well as parent metastable silicon structures (1.2 nm in diameter), was studied in cluster and PBC approaches using B3LYP/6-31G* and PW PP LDA approximations. The total density of states (TDOS) of the smallest quasispherical silicon quantum dot (Si 85 ) corresponds well to the TDOS of the bulk silicon. The elongated silicon nanodots and 1D nanowires demonstrate the metallic nature of the electronic structure. The surface oxidized layer opens the bandgap in the TDOS of the Si/SiO 2 species. The top of the valence band and the bottom of conductivity band of the particles are formed by the silicon core derived states. The energy width of the bandgap is determined by the length of the Si/SiO 2 clusters and demonstrates inverse dependence upon the size of the nanostructures. The theoretical data describes the size confinement effect in photoluminescence spectra of the silica embedded nanocrystalline silicon with high accuracy. * Correspondent author, e.mail: avramov.pavel@ jaea.go.jp +81 27 346 9670 +81 27 346 9696 1