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Characterization of the Individual Core/ Shell Silicon Nanowires

Marcin Marczak 1,2Jarosław Judek 1,2Anna Kozak 1Wojciech Gębicki 1Thierry Mélin 2Djamila Hourlier 2David Luxembourg 2

1. Warsaw University of Technology, Faculty of Physics, Koszykowa 75, Warszawa 00-662, Poland
2. Institut d'Electronique de Microelectronique et de Nanotechnologie, UMR CNRS 8520 (IEMN), BP 60069 - Cité scientifique-avenue Poincaré, Villeneuve d'Ascq 59652 Cedex, France


We report the results of a Raman scattering study of well-separated core/shell silicon nanowires grown by CVD (Chemical Vapor Deposition) and deposited on an Au surface. The diameters varies from around 100nm to 400nm. The analysis of Raman scattering shows a presence of both crystalline (520cm-1) and amorphous (470cm-1) phases of the silicon, forming quite independent fractions. From the growth conditions, nanowires are expected to form a core-shell cone, with the amorphous silicon phase (aSi) outside, and the crystalline silicon phase (cSi) inside.  Raman spectra have been analyzed in three points along the examined nanowire length: base, middle and tip. Based on the Stokes/anti-Stokes (St/aSt) ratios, the position and full width at half maximum of the Raman peaks temperatures of the amorphous shell and the cSi core were determined [1]. Against our expectations, the crystalline silicon (cSi) temperature was found lower than the amorphous silicon temperature (aSi) [Fig. 1]. This suggests that the nanowire cSi core is in a good thermal contact with the metallic substrate, thus improving the heat evacuation of the SiNW, for which the thermal conductivity is known to be low [2].

Fig. 1 Temperature of the silicon core and the amorphous shell obtained from St/aSt ratio for the 632nm laser line.

[1] Balkanski et al. Phys Rev B. 8, (1983) 1928

[2] Piscanec et al. Phys. Rev. B, 68, (2003) 241312


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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium J, by Marcin Marczak
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 14:25
Revised:   2009-06-07 00:48