Materials Science and Engineering B 174 (2010) 97–101 Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb The peculiarities of Si/SiO 2 interfaces in the Si–SiO 2 systems with Si nanocrystals T. Kryshtab a,∗ , G. Gómez Gasga a , N. Korsunska b , M. Baran b , S. Kirillova b , L. Khomenkova b , A. Sachenko b , T. Stara b , Y. Venger b , Y. Emirov c , Y. Goldstein d , E. Savir d , J. Jedrzejewski d a Instituto Politécnico Nacional, ESFM, Av. IPN, Ed. 9, U.P.A.L.M., 07738 Mexico D.F., Mexico b Institute of Semiconductor Physics of NASU, 45 Pr. Nauky, Kiev 03028, Ukraine c Nanotechnology and Nanomanufacturing Research Center, University of South Florida, Tampa, FL 33620, USA d Racah Institute of Physics, The Hebrew University, Jerusalem, Israel article info Article history: Received 31 August 2009 Received in revised form 2 April 2010 Accepted 25 April 2010 Keywords: Si-rich-SiO2 Magnetron sputtering Electron-paramagnetic resonance X-ray diffraction Photo-voltage abstract Si-rich-SiO 2 layers with excess silicon of 45–50% were grown by RF magnetron co-sputtering from pure SiO 2 and Si targets and were studied by Raman scattering, HRTEM, electron-paramagnetic resonance and X-ray diffraction (XRD) methods as well as by photo-voltage technique operated at different tempera- tures. The effect of Si substrate orientation of (1 1 1) or (1 0 0) on the layers properties was investigated. It was shown that high-temperature annealing in inert atmosphere stimulates a formation of Si crys- tallites in the film volume and of quartz crystallites near the layer/substrate interface. The dependences of the space orientation and the total volume of the formed quartz crystallites on substrate orientation were observed. The concentration of quartz crystallites in the films grown on the (1 0 0) Si substrate was found to be higher in several times than that in the films grown on the (1 1 1) Si substrate. The effect of the mechanical stresses on the layer–substrate interface states was observed for the layer prepared on the (1 1 1) Si substrate. It was shown that the natural oxidation of the layers before the annealing at high-temperature results in an increase of the positive fixed charge in the layer. At the same time it was found the formation of EX-centers containing Si vacancies close to crystallite/matrix interface. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Silicon nanostructures have drawn much attention due to the potential applications in development of integrated optoelectron- ics devices based on current Si technologies [1–3]. Si nanocrystals (Si-ncs) embedded in SiO 2 film are one of the most popular Si nanostructures for such optoelectronic appli- cations. The standard approaches of synthesizing Si-ncs include ion implantation of silicon into an amorphous SiO 2 -matrix [4] or deposition of Si substoichiometric oxide films using chemi- cal vapour deposition (CVD) [3,5,6], reactive evaporation [7,8] or sputtering [9]. The latter is performed by reactive SiO 2 sputter- ing in argon–hydrogen plasma [11] or by co-sputtering from Si and SiO 2 targets in pure argon plasma [18–23]. It is known that the properties of the produced layers depend strongly on depo- sition conditions (such as a temperature of substrate [12,13],a type of substrate [14], a target–substrate distance [15], plasma pressure [14], etc.) and post-deposition annealing [14,16]. A high- temperature annealing step (at 900–1200 ◦ C) is usually adopted ∗ Corresponding author at: Material Sciences, IPN–ESFM, Av. IPN, S/N, Ed. 9, U.P.A.L.M., c.p. 07738, Col. Lindavista, Mexico D.F., Mexico. Tel.: +52 55 57296000x55321; fax: +52 55 55862825. E-mail address: tkrysh@esfm.ipn.mx (T. Kryshtab). for the segregation of the excess Si. The induced Si-ncs can be amorphous or nanocrystalline depending on the annealing temperature. The Si-ncs sizes and their distribution in oxide matrix play an important role in light emitting and electronic properties of fab- ricated devices. On the other hand, the deposition of the layers on Si substrate is followed by formation of layer/substrate inter- face that plays an important role in the properties of the films. However, high-temperature annealing favours also the formation of the Si-ncs/oxide matrix interface that is also a key point that determines both the transport and the optical properties of the layers. There are few works devoted to the investigation of both inter- faces in such systems. However, some results were obtained. Thus, electron-paramagnetic resonance (EPR) and photoluminescence studies showed that the main non-radiative channel is connected with P b -centers located at Si-ncs/oxide interface [19,20]. An inves- tigation of capacitance–voltage (C–V) dependences revealed the effect of excess silicon on the electric charge accumulated in the layer [21]. However, the observed peculiarities of C–V characteris- tics did not allow to distinguish unambiguously the contribution of fast surface states (FSS) at layer/substrate interface and fixed charge in the layer. At the same time this information can be obtained by an investigation of temperature behaviour of photo- voltage. 0921-5107/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2010.04.027