(Invited) Using Surface Chemistry to Direct the Deposition of Nano-objects for Electronics

Abstract

Nano-objects, including nanowires, nanopores, nanochannels and nanorings, and two-dimensional materials have many applications in electronics, sensing, energy conversion, optoelectronics and non-linear optics. One of the major challenges in the practical use of these structures is their integration into complex functional structures in a predictable and controlled way. In this talk we will describe our progress in synthesizing in situ with precise placement both nano-objects and films of two-dimensional materials, in particular transition metal dichalcogenides. We have introduced two promising new techniques by which to direct the in situ growth of metallic and semiconducting nano-objects. ENDOM, or Electroless Nanowire Deposition On Micropatterned substrates, employs electroless deposition (ELD) to form metallic nanostructures on substrates. SENDOM, or Semiconductor Nanowire Deposition on Micropatterned surfaces, uses chemical bath deposition (CBD) to deposit semiconductor nanowires. Using these processes we demonstate the production of nanowires (diameters < 100 nm), mesowires (100 nm < diameter < ~3000 nm), nanorings, nanopores and nanochannels. These nanostructures can follow complex paths, such as arcs or right-angle bends, and are formed in parallel over cm2 areas. We will also discuss the formation of complex architectures, such as cross-bars, using these methods as well as the electrical properties of metallic nanowires deposited using ENDOM. Two-dimensional materials, such as transition metal dichalcogenides (TMDs), are currently widely sought after for their application in semiconductor and nanoelectronic devices. By using templated substrates such as highly oriented pyrolytic graphite (HOPG) and sapphire we have successfully deposited large area ultra-thin molybdenum disulfide films using CBD. Further we show that the polytype of molybdenum disulfide can be altered between 2H and 1T by depositing the film on substrates with different surface energies. As the surface energy of the substrate is increased the MoS2 deposit changes from 2H to 1T. We also demonstrate that by patterning the substrate with areas of different surface energies that patterned 2H and 1T MoS2 films can be grown in situ.