Nanoscale Size-Selective Deposition of Nanowires by Micrometer Scale Hydrophilic Patterns

Abstract

Controlling the post-growth assembly of nanowires is an important challenge in the development of functional bottom-up devices. Although various methods have been developed for the controlled assembly of nanowires, it is still a challenging issue to align selectively heterogeneous nanowires at desired spatial positions on the substrate. Here we report a size selective deposition and sequential alignment of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. Nanowires dispersed within oil were preferentially deposited only at a water/oil interface onto the hydrophilic patterns. The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns. Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns. We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon.

Nanoscale Thermal Management of Single SnO2 Nanowire: pico-Joule Energy Consumed Molecule Sensor

“…After the EBL and electrode deposition processes, the MgO sacrifice layer was removed by a dilute HCl solution (12 mM), resulting in a suspended nanowire device. It should be noted that the suspended nanowires were susceptible to attachment to the substrate in the final drying process, owing to a strong meniscus force. , To avoid this problem, instead of distilled water (surface tension of 72.8 mN/m at 20 °C), low surface tension solvent, such as ethanol (22.1 mN/m at 20 °C) or hydrofluoroether (HFE, 13.6 mN/m at 20 °C), was utilized in the final rinsing and drying process. More detailed procedures can be found in SI Figure S2.…”

Assembly of Gold Nanowires on Gold Nanostripe Arrays: Simulation and Experiment

“…Surface patterns can be powerful tools in the bottom-up assembly of nanomaterials by controlling the locations at which particles are assembled on the substrate as well as the geometry of the assembly. , For example, NWs have been deposited on/into lithographically fabricated electrodes on solid substrates and attracted/aligned there by electrophoretic forces. − Significant efforts have been directed toward achieving ordered NW and nanorod (NR) arrays via capillary assembly, in which convective flow and capillary forces that occur at an evaporating/receding liquid–solid interface can order and orient nanoparticles on a patterned substrate. ,,,,− Chemically patterned substrates have also been used to align NWs and NRs. ,− In this work, we adopt a relatively simple method, in which NWs in an aqueous suspension sediment onto a patterned substrate and are attracted to the pattern by van der Waals (vdW) forces. They subsequently diffuse and assemble on the patterned features, exhibiting a surprisingly diverse variety of ordered patterns.…”

Rational Concept for Reducing Growth Temperature in Vapor–Liquid–Solid Process of Metal Oxide Nanowires

“…These interesting features are hardly attainable by other nanowire growth methods. However, when compared with conventional liquid methods including hydrothermal nanowire synthesis, , the growth temperature range of VLS process is relatively high. , Typically, the growth temperatures of VLS growth of metal oxides were ranged from 600 to 1000 °C. − This high temperature operation frequently limits the application range of VLS method. Within the framework of VLS nanowire growth, the metal catalysts are required to be a liquid state, which essentially determines the range of growth temperature. , Although choosing the metal catalysts with lower melting points is a straightforward approach to reduce the growth temperature, it is frequently unfeasible due to the affinity between metal catalysts and desired materials of nanowires .…”

“…9 These interesting features are hardly attainable by other nanowire growth methods. However, when compared with conventional liquid methods including hydrothermal nanowire synthesis, 10,11 the growth temperature range of VLS process is relatively high. 12,13 Typically, the growth temperatures of VLS growth of metal oxides were ranged from 600 to 1000 °C.…”