Characterization of organosilane-modified silicon/silicon dioxide systems for biological and nanotechnology applications

Abstract

Silane functionalization of Si/SiO2 systems is a versatile technique that can be used in DNA microarray and nanotechnology applications. Control of the composition, chemistry and structure of the underlying silane film is crucial for optimization of the final devices. In this dissertation, aminosilanes and alkysilanes are investigated for applications in DNA microarrays and nanoparticle modification. Innovative methods are used to quantify the composition of these silane films, including X-ray photoelectron spectroscopy. In addition, low-temperature-plasma grown Si nanoparticles are modified for the first time using self-limited silanization techniques. Mixed silane monolayers provide a method for controlling DNA attachment via dilution of amine density. DNA hybridization results suggest these films are restrictive, thus reducing DNA hybridization efficiencies. To investigate the effect of the silane film structure on DNA hybridization, three distinct aminosilane films were generated: 1) a self-limited monolayer, 2) a 1-2 layer film and 3) a thick, multilayer film. DNA radiometric assays show restriction of DNA hybridization by the self-limited monolayer and high DNA hybridization efficiencies on the 1-2 layer film, demonstrating the important role the silane film structure plays in DNA microarray efficacy. This silane chemistry is extended to Si nanoparticles to improve their suitability for nanotechnology applications. Specifically, Si nanoparticles are modified with a monolayer-thick alkylsilane film, making them stable for over two months in air, and producing a colloidal suspension of the particles. The size, stability and colloidal suspension of these Si nanoparticles distinguish them as useful components for nanotechnology applications, such as light-emitting diodes, biological sensors and markers, and photovoltaics.