INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The Role of the Organic Layer Functionalization in the Formation of Silicon/Organic Layer/Metal Junctions with Coinage Metals
Autor/es:
E. M. PATRITO; F. A .SORIA; M. F. JUAREZ; P. PAREDES-OLIVERA
Lugar:
San Francisco
Reunión:
Congreso; 2012 Materials Research Society Spring Meeting; 2012
Institución organizadora:
Materials Research Society
Resumen:
Introducing organic molecules in electronics is limited by the ability to connect them electrically to the outside world. This involves the formation of top metal overlayers on the organic surfaces. This is not a trivial task because most known methods to make such contacts are likely to damage the molecules [1]. Understanding the atomic and molecular level interaction of metal atoms with organic surfaces is becoming increasingly important as the number of applications involving metal−organic interfaces grows. The design of silicon/alkyl layer/metal junctions for the formation of optimal top metal contacts requires the 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 developed a complete mechanistic and energetic picture of all the processes involved in the formation of silicon/alkyl layer/metal junctions. Our results are in agreement with the available experimental observations and provide detailed information on the reaction pathways and energy barriers involved in the formation of the junction. We performed a comprehensive density functional theory investigation to identity the reaction pathways of all the processes involved [2]. The diffusion of gold atoms through the alkyl layer was compared for two systems: compact alkyl monolayers on Si(111) and compact alkanethiol monolayers on Au(111). In the absence of a reactive terminal group, gold atoms penetrate through the monolayers with small energy barriers. However, the presence of thiol terminal groups introduces a high energy barrier which blocks the diffusion of metals into the monolayer. On the alkylated Si(111) surface, 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 understand the factors that influence the quality of top metal contacts during the formation of silicon/organic layer/metal junctions. [1] H. Haick and D. Cahen, Prog. Surf. Sci., 2008, 83, 217-261 [2] M. F. Juarez, F. A. Soria, E. M. Patrito, P. Paredes-Olivera. Phys. Chem. Chem. Phys. 2011, DOI: 10.1039/c1cp22360g