"Organic Monolayers on Hydrogen-terminated Silicon Surfaces"

M.E. ALASSIA; G.M. CHANS; G.I. LACCONI

New Hampshire, New London, Estados Unidos.

Conferencia; Gordon Research Conference on Electrodeposition.; 2004

Organic Monolayers on Hydrogen-terminated Silicon Surfaces M.E. Alassia; G.M. Chans; G.I. Lacconi. INFIQC, Depto. Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de La Torre y Medina Allende, Ciudad Universitaria, 5000 Córdoba, Argentina. Well-ordered and stable organic monolayers on crystalline silicon surfaces are potentially very interesting for many applications, e.g., in nonlinear optics and bio-adsorption experiments. In recent years, the preparation of dense alkyl monolayers covalently bonded to silicon surfaces has been reported [1-3]. The method makes use of the reaction between a hydrogen-terminated silicon surface and an 1-alkene, similarly to standard organic hydrosilylation reactions and it results in the formation of dense, well-ordered monolayers that are linked to the surface by a stable, covalent Si-C bond. In this communication, the preparation of stable monolayers on hydrogen-terminated Si(100) surfaces using nonfunctionalized 1-alkenes and cycloalkenes, is reported. The hydrogenated surface was characterized by ex-situ AFM and STM images as well as by electrochemical measurements by the oxide growth modification. The preparation of the monolayers was performed using neat 1-octadecene which reacts efficiently with the hydrogen-terminated Si(100) when heated to . The alkyl monolayer shows a high ability to passivate the surface and the oxidation of the modified surface occurs at more positive potentials. The monolayer formation reaction is assumed to be a radical-based process that starts at defects (e.g., a dangling bond) on the H-terminated surface. M.R. Linford, P. Fenter, P.M. Eisenberger, C.E.D. Chidsey, J. Am. Chem. Soc. 117 (1995) 3145. A.B. Sieval, V.Vleeming, H. Zuilhof, E.J.R. Sudhölter, Langmuir 15 (1999) 8288. L. Zhang, L. Li, S. Chen, S. Jiang, Langmuir 18 (2002) 5448. Acknowledgements: We thank CONICET, SECYT-UNC, Agencia Córdoba Ciencia S.E. and ANPCyT for their financial support.