Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Poster 1
HL 13.17: Poster
Montag, 26. März 2007, 15:00–17:30, Poster A
Light absorption of silicon nanoparticles — •Andreas Gondorf1, Cedrik Meier1, Stephan Lüttjohann1, Matthias Offer1, Axel Lorke1, and Hartmut Wiggers2 — 1Experimental Physics, University of Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany — 2Combustion and Gas Dynamics, University of Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany
We have studied silicon nanoparticles fabricated by gas-phase condensation and in-flight sintering using absorption and photoluminescence (PL) spectroscopy. We observe a quantum size effect in PL as well as in absorption spectroscopy. From an analysis of the absorption spectra we are able to identify the character of the band gap of the nanoparticles as indirect. This result is supported by measurements of the decay time of the photoluminescence of excitons. The decay time is four orders of magnitude larger than in direct semiconductors. Moreover, we are able to observe the influence of the particle size distribution in the absorption spectra. The size distribution follows the lognormal distribution. In order to explain the surprisingly small dependence of the absorption edge on the mean particle diameter, we discuss a model which takes into acount the lognormal size distribution.