Fabrication of heteronanorod structures by dynamic shadowing growth

Multilayered heterogeneous one-dimensional (1-D) nanostructures are important building blocks for nanodevice applications. A practical nanofabrication technique to produce heterogeneous nanostructures with arbitrary materials must have the ability to control the dimensions and uniformity, to control the alignment, and to control the interfacial properties of the heterogeneous nanostructures. In this paper, we demonstrate a simple but versatile method to fabricate three-dimensional (3-D) heterogeneous nanorod structures by multilayer dynamic shadowing growth (DSG). DSG is a process based on the geometric shadowing effect and substrate rotation in a physical vapor deposition system. By combining DSG and the sputtering technique, we successfully fabricated Au/Si matchstick nanorods which can further be developed as a novel biosensor for Respiratory Syncytial Virus (RSV) detection. By changing the source materials during the deposition, we demonstrate that complicated heterostructured nanorod arrays, such as Si/Ni multilayer nanosprings, can be easily produced, and they exhibit particular magnetic anisotropic behavior. We also use the DSG technique to coat a thin catalyst layer asymmetrically on the side of a nanorod backbone, and therefore design catalytic nanomotors with a variety of geometries capable of performing multiple desired motions in a fuel solution. This fabrication method reveals an optimistic step towards complex heteronanorod array design and fabrication.