Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 17: Poster Ib

HL 17.44: Poster

Freitag, 4. März 2005, 16:30–19:00, Poster TU F

Size dependent excitation energies of valence band plasmons in Si and SnO_x nanoparticles — •H Nienhaus, V Kravets, A Lorke, H Wiggers, M Kennedy, and F E Kruis — Sonderforschungsbereich 445, Universität Duisburg-Essen, 47048 Duisburg

Si and SnO_x nanoparticles with diameters in the range between 3 and 30 nm were produced in the gas phase and deposited on Au and Pd thin films. Structure and chemical composition were characterized by electron microscopy and Auger electron spectroscopy, respectively. By use of low electron energy-loss spectroscopy, electronic excitations of energies between 5 and 25 eV in the particles have been investigated. The energies of the valence band plasmons in both, Si and SnO_x, particles exhibit a strong size-dependence. Shifts of a few eV are observed when the diameter of the particle is reduced. The variation of the energy is found to be inversely proportional to the particle diameter. There are no significant changes of the excitation energy when varying the oxygen content of the tin oxide particles. In addition, energy losses due to interband transitions and core level ionization do not change with particle size.