Bio-functionalization of silicon carbide nanostructures for SiC nanowire-based sensors realization

The bio-functionalization process consisting in grafting desoxyribo nucleic acid via aminopropyl-triethoxysilane is performed on several kinds of silicon carbide nanostructures. Prior, the organic layer is characterized on planar surface with fluorescence microscopy and X-ray photoelectron spectroscopy. Then, the functionalization is performed on two kinds of nanopillar arrays. One is composed of top-down SiC nanopillars with a wide pitch of 5 microm while the other one is a dense array (pitch: 200 nm) of core-shell Si-SiC nanowires obtained by carburization of silicon nanowires. Depending on both the pillar morphology and the pitch, different results in term of DNA surface coverages are obtained, as seen from fluorescence microscopy images. Particularly, in the case of the wide pitch array, it has been shown that the DNA molecules are located all along the nanopillars. To achieve a DNA sensor based on a nanowire-field effect transistor, the functionalization must be conducted on a single SiC nanowire or nanopillar that constitutes the channel of the field effect transistor. The localization of the functionalization in a small area around the nanostructures guarantees high performances to the sensor. In this aim, the functionalization process is combined with common microelectronics techniques of lithography and lift-off. The DNA immobilization is investigated by fluorescence microscopy and atomic force microscopy.