Comparison of silicon nanocrystals size determination by Raman scattering and transmission electron microscopy measurements Jean Philippe Blondeau a, * , Caroline Andreazza b , Patrick Simon c , Francis Catan a , Le ´vi Allam a a Laboratoire dÕElectronique Signaux et Images, IUT de CHARTRES, Universite ´dÕOrle ´ans, 28000 Chartres, France b CRMD CNRS, 45067 Orle ´ans, France c CRMHT CNRS, 45067 Orle ´ans, France Received 27 May 2005; accepted 11 September 2005 Available online 1 December 2005 Abstract In the context of silicon nanoaggregates elaboration we have studied the Al–SiO 2 interface at temperatures under or above the eutectic point. We have reported the formation of diffusion limited aggregates (DLA) or deposition diffusion aggregates (DDA) of silicon. Raman scattering and X-ray analysis have proved the presence of crystalline silicon in these fractal structure and lead us to a typical elementary size in the nanometer range. TEM measurements confirm here the crystallite size and give informations on the silicon struc- ture in high resolution mode. The reaction of Al on SiO 2 seems to be a good way to form silicon nanocrystals in SiO 2 matrix of calibrate size. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Nanocrystalline silicon; Fractals; DLA; DDA; Raman scattering; TEM measurements 1. Introduction We have reported previously by in situ measurements that small crystallisations appeared during annealing of the Al/SiO 2 interface [1,2] above approximately 500 °C with quite uneven distributions and lead to the formation of fractal structure depending of the temperature. These interface has a big interest in both the field of electronic component and of composite materials [3–7] and more recently in the silicon based opto electronics [21]. We have previously revisited the crystallisations in the context of fractal growth. The introduction of the diffusion limited aggregation (DLA) [8–12] and of the deposition diffusion aggregation (DDA) models [13–16] have helped us to understand the morphologies linked to diffusion limited growth. From the morphological point of view, the DLA type of aggregates has a highly ramified structure whereas the DDA type structure is much denser, with a rough or ragged contour. Through X-ray analysis and Raman scattering measure- ments we have proved that these fractal structure are nano- crystalline silicon made. The broadening and the shift of the Si line have allowed us to conclude to a typical elemen- tary size of the structure in the nanometer range. The main purpose of this paper is to compare the size previously obtained by Raman scattering by the broaden- ing and the shift of the Si line and TEM measurements in the high resolution mode. We want to confirm that the typ- ical elementary size of the structure is in the nanometer range and they are silicon made. 0925-3467/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2005.09.073 * Corresponding author. E-mail address: jean-philippe.blondeau@univ-orleans.fr (J.P. Blon- deau). www.elsevier.com/locate/optmat Optical Materials 29 (2006) 279–286