Gold-silicon nanofiber synthesized by femtosecond laser radiation for enhanced light absorptance

In this study, we devised a new concept for the precise nanofabrication of Au-Si fibrous nanostructures using megahertz femtosecond laser irradiation in air and atmospheric pressure conditions. The weblike fibrous nanostructures of Au thin layer on silicon substrate, which are proposed for the application of solar cells, exhibit a specific improvement of the optical properties in visible wavelength. Varying numbers of laser interaction pulses were used to control the synthesis of the nanofibrous structures. Electron microscopy analysis revealed that the nanostructures are formed due to the aggregation of polycrystalline nanoparticles of the respective constituent materials with diameters varying between 30 and 90 nm. Measurement of the reflectance through a spectroradiometer showed that the coupling of incident electromagnetic irradiation was greatly improved over the broadband wavelength range. Lower reflectance intensity was obtained with a higher number of laser pulses due to the bulk of gold nanoparticles being agglomerated by the mechanism of fusion. This forms interweaving fibrous nanostructures which reveal a certain degree of assembly.