Seeded silicon nanowire growth catalyzed by commercially available bulk metals: broad selection of metal catalysts, superior field emission performance, and versatile nanowire/metal architectures

Over the past two decades, metal-seeded growth has been the most widely used method for Si nanowire synthesis. However, preparation methods of metal catalysts mostly involve indirect, multi-step procedures and suffer from many processing limitations. In this study, we demonstrate that bulk metals can be directly used as catalysts for seeded Si nanowire growth. Eight metals which cover all three types of metals used for Si nanowire growth, such as Ag, Al, Au, Cu, Fe, Ni, Pb and Ti, were explored as catalysts. Single crystalline Si nanowires were synthesized in the presence of bulk Ag, Al, Cu, Fe, Ni, Pb, and Ti at temperatures ranging from 450 to 550 degrees C at 10.3 MPa, whereas no wires were produced in the presence of bulk Au. The metals effective for seeded growth are cheap, easily obtained, and exhibit excellent catalytic reusability. In addition, as-grown Si nanowires exhibit superior field emission property due to their good electrical contact between the wire and metal interface. Various nanowire/ metal substrate architectures could be achieved through the use of metals with different morphologies. Compared to the traditional seeded-growth protocol, bulk metal-catalyzed growth provides a more facile and flexible synthetic scheme and a direct route to grow Si nanowires on metal substrates for advanced nanowire applications.