Investigation of nc-Si inclusions in multilayer a-Si:H films obtained using the layer by layer technique A.S. Gudovskikh a, * , J.P. Kleider a , V.P. Afanasjev b , A.Z. Kazak-Kazakevich b , A.P. Sazanov b a Laboratoire de G enie Electrique de Paris/Sup elec (UMR 8507 CNRS), Ecole Superieure d’Electriticite Univ. Paris VI et XI, 11 Rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette cedex, France b St.-Petersburg State Electrotechnical University, Department of Microelectronics, Prof. Popov Str. 5, St.-Petersburg, RU-197376, Russia Available online 24 March 2004 Abstract The development of the nanocrystalline silicon inclusions in homogeneous and multilayered a-Si:H films was investigated by transmission electron microscopy (TEM). The homogeneous a-Si:H films were obtained by continuous deposition at constant gas mixture (CGM) mode and the multilayered films were obtained by the layer by layer (LBL) method, i.e. using intermediate annealing in hydrogen plasma. Initial CGM and LBL films were completely homogeneous and amorphous. After annealing at 450 °C approximately the same volume fraction (1–2%) and size (10 nm) of nc-Si inclusions was observed in both CGM and LBL films. However, after annealing at 750 °C CGM films became polycrystalline with a grain size of about 1 lm, while LBL films were nanocrystalline with nc-Si average size of 10 nm, which did not exceed the layer thickness deposited per cycle. This effect gives a new way of controlling the size and amount of nanocrystalline inclusions in a-Si:H films. Ó 2004 Elsevier B.V. All rights reserved. PACS: 61.82.Rx; 81.15.Gh; 81.40.)z 1. Introduction Silicon films containing nanocrystalline silicon inclu- sions are attractive for effective luminescent devices in the visible spectral range due to quantum size effects in the Si nanocrystallites. However, the luminescent properties of these films strongly depend on size and volume fraction of nanocrystallites (nc-Si) [1,2]. There- fore an accurate control of them is required. The simplest way to fabricate films with nc-Si inclu- sions is plasma enhanced chemical vapor deposition (PECVD) using silane highly diluted into hydrogen [3]. But even playing with the parameters of the deposition process, it is rather difficult to obtain nc-Si inclusions with required size and concentration. The other way to obtain films with nc-Si inclusions is deposition of SiO 2 /Si superlattice structures with further high temperature annealing. Using the SiO 2 intermedi- ate layers allows one to control the nc-Si size by changing the thickness of the Si layer [4,5]. Although promising photoluminescence properties were achieved in this type of superlattice structures [6,7], the presence of the dielectric SiO 2 layers hinders the charge carrier transport and therefore electroluminescence may hardly be obtained. We here study a new way of control of the size and amount of nc-Si inclusions in a-Si:H films using a combination of layer by layer (LBL) deposition tech- nique and high temperature annealing. 2. Experiment The films were deposited by PECVD (13.56 MHz) on NaCl substrates at a substrate temperature of 250 °C. Details of our experimental apparatus are described elsewhere [8]. Films were fabricated at two different modes: (i) continuous deposition of the homogeneous a- Si:H films at constant gas mixture (CGM) mode; (ii) layer by layer (LBL) deposition using intermediate * Corresponding author. Tel.: +33-1 6985 1680; fax: +33-1 6941 8318. E-mail address: goudovskih@lgep.supelec.fr (A.S. Gudovskikh). 0022-3093/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2004.02.038 Journal of Non-Crystalline Solids 338–340 (2004) 135–138 www.elsevier.com/locate/jnoncrysol