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P: Fachverband Plasmaphysik
P 4: Staubige Plasmen
P 4.5: Talk
Monday, March 30, 2009, 17:40–17:55, HS Biochemie (groß)
Generation of silicon nanoparticles in plasma — •Angelo Consoli, Max Zimmermann, Jan Benedikt, and Achim von Keudell — Center for Plasma Science and Technology, Ruhr-Universität Bochum, 44780 Bochum
Nanoparticles are of key interest in many applications. For example they may serve as quantum dots in electric devices, as photoluminescent marker for medical diagnostics or as gas carrier for nanodisperse catalysts. A convenient way to generate nanoparticles is the synthesis in reactive plasma, fed by i.e. silane, acetylene, or a combination of molecular gases. Particles are inherently grown is such plasmas. The problem, however, is to tailor particles characteristics such as diameter and composition in a controlled way. To overcome this hurdle we study the formation of Si-nanoparticles in silane plasma as first step to compound-particles (i.e. SiCN). The neutral plasma chemistry is followed time resolved by molecular beam mass spectrometry. Bayes analysis is used to analyze the mass spectra and yields the time evolution of SiH4, Si2H6 and Si3H8 densities. Nanoparticles, in our experiment, are extracted from the plasma volume by means of electric fields and accelerated onto a substrate. The particle size is manipulated by varying the time delay between plasma ignition and extraction. AFM measurements of extracted particles show mean particle diameters of 2-5nm and corresponding fairly narrow size distributions. Room temperature photoluminescence emission is detected and its peak varies with particle mean size, as expected.