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Issue 48, 2011
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The role of the organic layer functionalization in the formation of silicon/organic layer/metal junctions with coinage metals

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Abstract

The design of silicon/alkyl layer/metal junctions for the formation of optimal top metal contacts requires knowledge of the mechanistic and energetic aspects of the interactions of metal atoms with the modified surface. This involves (a) the interaction of the metal with the terminal groups of the organic layer, (b) the diffusion of metal atoms through the organic layer and (c) the reactions of metal atoms with the silicon surface atoms. The diffusion through the monolayer and the metal catalyzed breakage of Si–C bonds must be avoided to obtain high quality junctions. In this work, we performed a comprehensive density functional theory investigation to identify the reaction pathways of all these processes. In the absence of a reactive terminal group, gold atoms may penetrate through a compact alkyl monolayer on Si(111) with no energy barrier. However, the presence of thiol terminal groups introduces a high energy barrier which blocks the diffusion of metals into the monolayer. The diffusion barriers increase in the order Ag < Au < Cu and correlate with the stability of metal–thiolate complexes whereas the barriers for the formation of metal silicides increase in the order Cu < Au < Ag in correlation with the increasing metallic radii. The reactivity of gold clusters with functionalized Si(111) surfaces was also investigated. Metal silicide formation can only be avoided by a compact monolayer terminated by a reactive functional group. The mechanistic and energetic picture obtained in this work contributes to understanding of the factors that influence the quality of top metal contacts during the formation of silicon/organic layer/metal junctions.

Graphical abstract: The role of the organic layer functionalization in the formation of silicon/organic layer/metal junctions with coinage metals

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Publication details

The article was received on 20 Jul 2011, accepted on 07 Oct 2011 and first published on 01 Nov 2011


Article type: Paper
DOI: 10.1039/C1CP22360G
Citation: Phys. Chem. Chem. Phys., 2011,13, 21411-21422
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    The role of the organic layer functionalization in the formation of silicon/organic layer/metal junctions with coinage metals

    M. F. Juarez, F. A. Soria, E. M. Patrito and P. Paredes-Olivera, Phys. Chem. Chem. Phys., 2011, 13, 21411
    DOI: 10.1039/C1CP22360G

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