PLASMONIC PLATFORMS DESIGN: INFLUENCE OF THE PRETREATMENT OF Si (111) ON THE FUNCTIONALIZATION WITH APTES TO OPTIMIZE THE SURFACE ANCHORING OF Au NPs

J. KLUG; L.A. PÉREZ; E.A. CORONADO; G.I. LACCONI

Workshop; PLASMONS 2011.; 2011

PLASMONIC PLATFORMS DESIGN: INFLUENCE OF THE PRETREATMENT OF Si (111) ON THE FUNCTIONALIZATION WITH APTES TO OPTIMIZE THE SURFACE ANCHORING OF Au NPs Joaquín Klug, Luis A. Pérez, Eduardo A. Coronado, Gabriela I, Lacconi INFIQC, Dpto. de Fisicoquímica, Fac. de Cs. Químicas. UNC, Medina Allende y Haya de la Torre, Ciudad Universitaria, X5000HUA, Córdoba, ARGENTINA jklug@fcq.unc.edu.ar Design of silicon platform containing arrays of gold nanoparticles (NPs) is currently a very important area because of their diverse applications such as microelectronics, optical and spectroscopic sensors, etc. [1]. Synthesis of robust platforms for the above applications requires the optimization of the NPs-substrate interaction. This is achieved by careful control of the pretreatment of the substrate, selection of the molecule for the surface functionalization and the characteristics of NPs (type of metal, size, shape and dielectric environment). The goal of the present work is to study the optimal conditions for the plasmonic platforms by optimizing the interaction between gold NPs and the substrate. Different kinds of substrates were chosen to compare their performance: n-Si(111)-H, Si-Oxq (silicon oxide produced by chemical methods) or Si-Ox-eq (silicon oxide generated by electrochemical methods). The hydrogenation of the silicon surface was performed by immersion of the silicon substrate in HF/NH4F solution. Chemical oxidation was achieved with piranha solution at 80 ºC. The anodic oxidation was carried out by potenciostatic and potentiodynamic control [2]. All the substrates, subject of the above treatments were modified with aminopropyl-triethoxysilane (APTES) at different concentrations to form a monolayer film with –NH2 terminal groups. The degree of coverage of the surface with Au NPs depends on the structure of the APTES monolayer (APTES concentration) and the pretreatment of the substrate. It was found that almost homogeneous distribution of Au NPs was obtained when the pretreatment was performed by electrochemical methods and at low concentration of APTES. The enhancement of the Raman scattering signal of Rhodamine 6G molecules at 633 nm was used as a probe of the degree of coverage of silicon surface. The spectroscopic results are in agreement with SEM characterization of the array of gold NPs in the platform.