Large-scale assembly of semiconductor nanowires into desired patterns for sensor applications

Abstract

The capability to rationally assemble semiconductor nanostructures into desired patterns is vital to their applications in functional devices. Here we report a facile method to assemble silicon nanowires (SiNWs) into large-area desired patterns by applying an external alternating electrical field between two photoresist-patterned indium tin oxide (ITO) electrodes. By manipulating the electrode geometries through photolithography, pattern shapes can be tuned, from parallel strips, concentric circles, grid-like structures to square windows. The patterns can be firmly preserved on the substrate after the removal of photoresist, and can be readily transferred onto a flexible and insulating substrate for further device applications. These NW patterns formed on the polydimethylsiloxane (PDMS) flexible substrate found excellent applications as both humidity and optical sensors with outstanding device stability and reproducibility. Moreover, it was found that the silver nanoparticle decorated-SiNW (AgNPs@SiNW) patterns could serve as an excellent surface-enhanced Raman scattering (SERS) substrate for sensing Rhodamine 6G (R6G) molecules.