"Organic Monolayers on Hydrogen-terminated Silicon Surfaces"

G.I. LACCONI

Berlin, Alemania

Congreso; 3rd Gerischer Symposium. Electrocatalysis: Theory and Experiment.; 2005

3. Gerischer-Symposium. Electrocatalysis: Theory and Experiment. Berlin, 6 - 8 July 2005 Organic Monolayers on Hydrogen-terminated Silicon Surfaces 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. E-mail: glacconi@mail.fcq.unc.edu.ar Well-ordered and stable organic monolayers on crystalline silicon surfaces are potentially interesting for many applications, e.g., in nonlinear optics and bio-adsorption phenomena. The chemical surface modification of the hydrogen-terminated Si surface to prepare a molecularly well-defined protective interface that imparts improved stability to the surface, is also important. Recently, the preparation of dense alkyl monolayers covalently bonded to silicon surfaces has been reported [1-4]. The method makes use of the reaction between a hydrogen-terminated silicon surface and an 1-alkene, similarly to standard organic hydrosilylation reactions. Formation of dense, well-ordered monolayers that are linked to the surface by a stable, covalent Si-C bond, is obtained. In this communication, the preparation of hydrogen-terminated Si(100) surfaces derivatized with covalently attached alkyl chains and aromatic alkyl stable monolayers using radical based olefin addition methods is reported. The structural characterization of the surfaces derivatized through the use of such covalent Si-C linkages was performed by ex-situ AFM and STM. In addition, the electrochemical properties of organic-modified silicon surfaces related to the oxide growth were established. The preparation of the monolayers was performed using neat 1-octadecene or allyl-bencene, which react efficiently with the hydrogen-terminated Si(100) when heated at temperatures over 130ºC. The monolayer formation reactions are assumed to be a radical-based process thermally induced that starts at a defect (e.g., a dangling bond) at the H-terminated surface. Cyclic voltammetry and electrochemical impedance results show a high ability to passivate the silicon surface by the organic monolayers. Direct correlations between the coverage and the electrical properties of the film with the potential for the silicon oxide electroformation are performed. 1. M.R. Linford, P. Fenter, P.M. Eisenberger, C.E.D. Chidsey, J. Am. Chem. Soc. 117 (1995) 3145. 2. A.B. Sieval, V.Vleeming, H. Zuilhof, E.J.R. Sudhölter, Langmuir 15 (1999) 8288. 3. L. Zhang, L. Li, S. Chen, S. Jiang, Langmuir 18 (2002) 5448. 4. P. Allongue, C.H. de Villeneuve, G. Cherouvrier, R. Cortes, M.C. Bernard, J. Electroanal. Chem. 550-551 (2003) 161. Acknowledgements: The author is grateful to CONICET, SECYT-UNC, Agencia Córdoba Ciencia S.E., ANPCyT and Alexander von Humboldt Foundation for their financial support. 2. A.B. Sieval, V.Vleeming, H. Zuilhof, E.J.R. Sudhölter, Langmuir 15 (1999) 8288. 3. L. Zhang, L. Li, S. Chen, S. Jiang, Langmuir 18 (2002) 5448. 4. P. Allongue, C.H. de Villeneuve, G. Cherouvrier, R. Cortes, M.C. Bernard, J. Electroanal. Chem. 550-551 (2003) 161. Acknowledgements: The author is grateful to CONICET, SECYT-UNC, Agencia Córdoba Ciencia S.E., ANPCyT and Alexander von Humboldt Foundation for their financial support. 1. M.R. Linford, P. Fenter, P.M. Eisenberger, C.E.D. Chidsey, J. Am. Chem. Soc. 117 (1995) 3145. 2. A.B. Sieval, V.Vleeming, H. Zuilhof, E.J.R. Sudhölter, Langmuir 15 (1999) 8288. 3. L. Zhang, L. Li, S. Chen, S. Jiang, Langmuir 18 (2002) 5448. 4. P. Allongue, C.H. de Villeneuve, G. Cherouvrier, R. Cortes, M.C. Bernard, J. Electroanal. Chem. 550-551 (2003) 161. Acknowledgements: The author is grateful to CONICET, SECYT-UNC, Agencia Córdoba Ciencia S.E., ANPCyT and Alexander von Humboldt Foundation for their financial support. M.R. Linford, P. Fenter, P.M. Eisenberger, C.E.D. Chidsey, J. Am. Chem. Soc. 117 (1995) 3145. 2. A.B. Sieval, V.Vleeming, H. Zuilhof, E.J.R. Sudhölter, Langmuir 15 (1999) 8288. 3. L. Zhang, L. Li, S. Chen, S. Jiang, Langmuir 18 (2002) 5448. 4. P. Allongue, C.H. de Villeneuve, G. Cherouvrier, R. Cortes, M.C. Bernard, J. Electroanal. Chem. 550-551 (2003) 161. Acknowledgements: The author is grateful to CONICET, SECYT-UNC, Agencia Córdoba Ciencia S.E., ANPCyT and Alexander von Humboldt Foundation for their financial support.