Multi-scale modelling of silicon nanocrystal synthesis by Low Pressure Chemical Vapor Deposition

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• 作者：I. Zahi^a ;   ; ^b ;   ; ^c ; P. Mur^b ; Ph. Blaise^b ; A. Estè ; ve^c ; M. Djafari Rouhani^c ; H. Vergnes^a ; B. Caussat^a ;   ; ^{Brigitte.Caussat@ensiacet.fr}
• 关键词：Chemical vapour deposition ; Silicon ; Modelling ; Density Functional Theory ; Multi-scale approach ; Nanocrystals
• 刊名：Thin Solid Films
• 出版年：2011
• 出版时间：1 September 2011
• 年：2011
• 卷：519
• 期：22
• 页码：7650-7658
• 全文大小：929 K
• ISSN：S0040609011011485

文摘

A multi-scale model has been developed in order to represent the nucleation and growth phenomena taking place during silicon nanocrystal (NC) synthesis on SiO₂ substrates by Low Pressure Chemical Vapor Deposition from pure silane SiH₄. Intrinsic sticking coefficients and H₂ desorption kinetic parameters were established by ab initio modelling for the first three stages of silicon chemisorption on SiO₂ sites, i.e. silanol Si―OH bonds and siloxane Si―O―Si bridges. This ab initio study has revealed that silane cannot directly chemisorb on SiO₂ sites, the first silicon chemisorption proceeds from homogeneously born unsaturated species like silylene SiH₂. These kinetic data were implemented into the Computational Fluid Dynamics Fluent code at the industrial reactor scale, by activating its system of surface site control in transient conditions. NC area densities and radii deduced from Fluent calculations were validated by comparison with experimental data. Information about the deposition mechanisms was then obtained. In particular, hydrogen desorption has been identified as the main limiting step of NC nucleation and growth, and the NC growth rate highly increases with run duration due to the autocatalytic nature of deposition.