Nanotråd

Nanotråd, or nanowire, is a nanoscale filament with a diameter ranging from a few nanometers to hundreds of nanometers and lengths that can extend to micrometers, yielding a high aspect ratio. Depending on synthesis, they can be single-crystalline or polycrystalline and may exhibit quantum confinement effects that influence electrical and optical behavior. Nanowires are studied across materials systems and have potential as building blocks for nanoscale devices.

Fabrication methods: Top-down approaches start from bulk materials and use lithography and etching to define nanowire geometries. Bottom-up approaches rely on chemical vapor deposition, vapor–liquid–solid growth, molecular beam epitaxy, or solution-based synthesis to nucleate and fuse nanowire crystals. Template-assisted methods use porous membranes to guide growth.

Materials: semiconductors such as silicon, gallium nitride, zinc oxide, or indium phosphide; metals like gold or platinum; and various oxides and compound semiconductors. Carbon nanotubes are distinct nanoscale filaments and are not always categorized as nanowires, though some developers use the term loosely.

Applications: nanoscale transistors, sensors (chemical, biological), photonic components (waveguides, LEDs), energy devices (photovoltaics, supercapacitors, battery electrodes), and NEMS. Their large surface-to-volume ratio and flexibility enable novel device architectures, including flexible electronics and biointerfaces.

Characterization and challenges: characterization by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, Raman spectroscopy, and electrical testing. Challenges include controlling growth reproducibility, surface states and defects, environmental stability, scalable integration with existing manufacturing, and reproducible electrical contact formation.