"Covalently attached Monolayers on crystalline Hydrogen-terminated Silicon?

C. I. VÁZQUEZ; M. B. QUIROGA ARGAÑARAZ; G. I. LACCONI

La Palma, España

Congreso; 2nd ECHEMS Meeting. "Electrochemistry in Surface Functionalization"; 2006

Covalently attached Monolayers on crystalline Hydrogen-terminated Silicon Cecilia I. Vázquez, Bernarda Quiroga Argañaraz, Gabriela .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   Organic monolayers are an emerging area of research in nanoelectronics [1]. Possible future applications of these molecular layers include organic transistors, sensors in biochemistry and biophysics and hybrid silicon-molecular memory applications (in flash or dynamic random access memory) [2,3]. Other (perhaps, more immediate) applications include passivation, patterning, and control of the chemical and physical properties of interfaces [4]. Determination of the electrical properties of the interfaces between the organic monolayers and the semiconductor substrates, particularly charge trapping at and charge transport across the silicon/organic interfaces, are key issues common to all the above applications of molecular nanoelectronics. Also common to the success of these applications is the realization of a stable, densely packed, organic monolayer, covalently bonded directly to the silicon surface [5-7]. The purpose of this work was the formation and characterization of hidrogen-terminated Si(111) surfaces derivatized with covalently attached alkyl chains and aromatic alkyl monolayers. The synthesis of the monolayers was performed using neat 1-octadecene or styrene, which react efficiently with the hydrogen-terminated Si(111) when heated at temperatures over 140ºC or under exposition to UV radiation (l = 254 nm). The monolayer formation reactions are assumed to be a radical-based process thermally or photochemically induced, that starts at a defect (e.g., a dangling bond) at the H-terminated surface. The electrochemical charaterization of the organically functionalized silicon surface was performed by cyclic voltammetry and electrochemical impedance, related to its ability to ,