Electroless nanoworm Au films on columnar porous silicon layers

A characterization study of nanoworm Au thin films fabricated onto Si (100) using an intermediate columnar porous silicon (PSi) layer is presented. The Au thin films are resistant to peeling in different buffers and solvents. Adhesion arises from the presence of a diffused Au nucleation layer in the channeled PSi, which can be observed even at short electroless Au deposition times. For longer deposition times, a gold surface film grows from piled and aggregated Au crystals, providing high surface area. X-ray absorption spectroscopy studies revealed differences in the Au L3 absorption edge that can be ascribed to the induced nanoworm structure. The optical behavior of the Au grown on the surface has also been studied by light reflectance spectroscopy and related to the characteristic Au intra-band absorption. Such surfaces could enhance the performance of electric or optical devices with sensitivity limited by surface area availability.

► We fabricate gold structures on porous silicon by an electroless process. ► The columnar porous silicon induces the growth of nanoworm structures. ► Gold remains adherent due to the formation of a gold diffusion layer. ► The X-ray absorption spectra support the presence of a nanostructured Au layer. ► Reflectance measurements indicate that the Au film behaves as a continuous layer.