Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Poster Session III - MA 141/144 (Methods: Atomic and Electronic Structure; Particles and Clusters; Heterogeneous Catalysis; Semiconductor Substrates: Epitaxy and Growth+Adsorption+Clean Surfaces+Solid-Liquid Interfaces; Oxides and Insulators: Solid-Liquid Interfaces+Epitaxy and Growth; Phase Transitions; Metal Substrates: Adsorption of Inorganic Molecules+Epitaxy and Growth; Surface Chemical Reactions; Bimetallic Nanosystems: Tuning Physical and Chemical Properties; Oxides and insulators: Adsorption; Organic, polymeric, biomolecular films; etc.)
O 55.10: Poster
Mittwoch, 27. Februar 2008, 18:30–19:30, Poster F
Ab initio study on electronic and optical properties of silicon nanocrystals embedded in SiO2 matrices — •Kaori Seino1, Friedhelm Bechstedt1, and Peter Kroll2 — 1Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Jena, Germany — 2Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, USA
Although a high control of size and arrangement of Si nanocrystals (NCs) embedded in a SiO2 can be obtained experimentally, theoretical works for Si NCs embedded in SiO2 are limited. We study electronic and optical properties for Si NCs embedded in an amorphous SiO2 matrix by means of first-principles calculations. Many theoretical results are available for hydrogenated Si NCs. We investigate the dependence on the diameter of the Si NCs, varying in the range from 0.8 to 1.6 nm. The calculations for optical properties have been widely performed within the independent-particle approximation. The results for Si NCs embedded in SiO2 are compared with the corresponding results for hydrogenated Si NCs of the same size. The electronic confinement effects are much reduced with respect to crystallites without host. The optical absorption spectra show a pronounced peak somewhat blueshifted to the bulk E2 peak similarly to measured spectra. We extract dielectric functions of the NC material from the calculated spectra using different effective-medium theories.