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p-type silicon electrode modification with ferrocene. Effect of the distance electrode-molecule in its electric properties.

Gonzalo Riveros 1Sebastián Meneses 2

1. Universidad de Valparaíso (UV), Avenida Gran Bretaña 1111, Playa ancha, Valparaíso, Valparaíso 2340000, Chile
2. Pontificia Universidad Católica de Valparaíso (PUCV), Avda Brasil 2950, Valparaíso Chile, Valparaíso xxxx, Chile

Abstract

The formation of a hybrid semiconductor-molecule is a feasible alternative to extend silicon properties to a molecular scale so it can be applied to the development of nanoelectronic devices. In this field, there are many studies that exhibit the union of different organic and organometallic molecules to the silicon surface by way of different routes (UV activation, UHV). Moreover, the union of active redox molecules, specifically porphyrins, to the silicon surface is a complicated procedure, mainly due to previous synthesis and characterization of these molecules. On the other hand, the use of derived molecules of ferrocene is limited to a few compounds commercially acquired, thus restricting potential research of these systems. Therefore, this study shows an alternative route for the modification of silicon using derived molecules of ferrocene anchored by an alkyl chain of variable length. The modification is carried out by adding a double bond of an alkene halide to the H-terminated silicon surface activated by white light and its subsequent reaction with monolithio ferrocene. Of this way, only the ferrocene molecule is linked to the carbon chain previously anchored to the silicon, thus avoiding the forming of by-products onto the surface. This method paves the way for a systematic study of the effect that the length of the chain will have on the electric properties of these hybrid materials. Chains with 3 and 5 carbon chains equipped with ferrocene terminals were linked to (100) p-type silicon. AFM images and contact angle measurement where put into effect in order to characterize the modified surface. The electric properties of both samples were determined by cyclic voltammetry, AC voltammetry, open circuit potential amperometry and electrochemical impedance spectroscopy measurement. All of them exhibited variations related with the length of the carbon chain.

Acknowledegements. This work was supported by FONDECYT-Chile (Grant N° 1050700).

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2007, Symposium B, by Gonzalo Riveros
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-17 16:59
Revised:   2009-06-07 00:44