An atomic-scale study of hydrogenated silicon cluster deposition on a crystalline silicon surface Ning Ning ⁎, Steven M. Rinaldi, Holger Vach LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France abstract article info Available online 21 February 2009 Keywords: Molecular dynamics simulations Hydrogenated silicon clusters Deposition mechanism Silicon surface Controlled deposition of clusters on solid surfaces has attracted lots of attention in recent years, because of its potential application to tailoring the desired electronic properties of the resulting surfaces. We have carried out an atomic-scale study to understand the deposition mechanism. The molecular dynamics approach based on a modified Tersoff potential is used to simulate the deposition mechanism of hydrogenated silicon clusters on a crystalline silicon surface in detail. The important factors governing the deposition process such as impact energy and substrate temperature, are investigated for the hydrogenated silicon cluster Si 29 H 24 on a H-terminated Si(100)-(2x1) surface. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The controlled deposition of clusters on solid surfaces has attracted a lot of attention in recent years due to its potential application in tailoring the electronic properties of the resulting thin film. In particular, two types of deposition mechanisms are attractive: the destructive deposition of clusters and the soft- landing of cluster. Destructive deposition, e.g., ionized cluster deposition, holds promise in synthesizing high quality thin films at low temperatures. In this mechanism, the impact energy of the cluster is transferred to the fragmentary cluster atoms, thus becoming migration energy, and leading to high atomic mobility on the surface even at low temperatures [1]. In soft-landing deposition, the cluster is not destroyed upon landing on the substrate. This type of deposition is equally promising, as clusters exhibit interesting quantum properties [2,3] that are sensitive to their size and bonding states, and which can therefore be controlled. In both cases, the deposition of clusters instead of individual atoms or molecules attracts industrial applications due to its inherent possibility of high-speed thin film deposition. In this work, we used model potential molecular dynamics simulations to study the controlled deposition of clusters on solid surfaces in order to understand the growth mechanisms and conditions. We begin our research with the simulation of the deposition of hydrogenated silicon clusters under low temperature plasma-enhanced chemical vapor deposition conditions. 2. Computational methods To simulate the nanoparticle-surface interaction, the Ohira–Tersoff (OT) potential was employed as it has been shown to have a good performance in describing the structure and properties of amorphous Si (a-Si) bulk phases [4] and c-Si surfaces [5], and because it has been successfully used to study the radical–surface interactions [6–8], a-Si thin film growth mechanisms [9–11], and the H-induced crystallization of a-Si thin films [12–14]. The potential function form is described in [15]. The performance of the OT potential in describing the structure and properties of c-Si bulk is given in Table 1 , which shows that the results of the OT potential are in good agreement with ab initio calculation results. In this study, the filled fullerene stable configuration Si 29 H 24 shown in Fig. 1 has been chosen to be the impinging cluster, as the structural and optical properties of this 1 nm nanoparticle have been studied and compared to theoretical and experimental findings [17,18]. The H-terminated Si(100)-(2x1) surface is used as the substrate, which consists of 288 silicon atoms (see Fig. 2). The dimension of this substrate is 21.72 Å×21.72 Å×10.86 Å with 2 dimensional periodic boundary conditions (PBC) applied in the surface plane. The top silicon layer is a reconstructed layer consisting of silicon dimers. The bottom two layers are kept rigid in their equilibrium positions to avoid translation of the substrate in space. The substrate temperature is controlled by using a Berendsen thermostat [19] in the three layers above the rigid layers. These three layers also act as a heat reservoir which absorbs the heat during the collision. We used two substrate temperatures which represent the two extreme values employed in low temperature PECVD: 373 K and 573 K. The surface was heated up to the target temperature. Then, the surface temperature was maintained until the surface structure reached its equilibrium state, which took about 10 ps. Afterwards, the deposition of the Si 29 H 24 cluster on the substrate was initiated. The Thin Solid Films 517 (2009) 6234–6238 ⁎ Corresponding author. E-mail address: ning@leonardo.polytechnique.fr (N. Ning). 0040-6090/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2009.02.086 Contents lists available at ScienceDirect Thin Solid Films journal homepage: www.elsevier.com/locate/tsf