Nanowires are just like normal electrical wires other than the fact that they are extremely small. Like conventional wires, nanowires can be made from a variety of conducting and semiconducting materials like copper, silver, gold, iron, silicon, zinc oxide and germanium. Nanowires can also be made from carbon nanotubes.
Nanowires are less than 100 nanometers in diameter and can be as small as 3 nanometers. Typically nanowires are more than 1000 times longer than their diameter. This massive difference in the length to diameter ratio means than nanowires are often referred to as 1-dimensional materials. This leads to unique properties that are not seen in the bulk materials, such as Quantum Mechanical Effects.
Quantum Mechanical Effects
The minute size of nanowires means that quantum mechanical effects become important. “Quantum Wires” exploit quantum mechanics to produce wires with a range of unique electrical properties. These properties include Quantum Tunnelling that allows wires made from carbon nanotubes to have extremely high conductivity with electrons travelling ballistically through the wire.
Defects, edge effects and scattering caused when nanowire width is below the free electron mean free path of the wire material, means nanowires made from metals can have conductivity much lower than that for the bulk material.
Nanowires show promise for use in applications including:
• Exceptionally small electronic circuits
• Memory devices
• Advanced composite materials
• Quantum devices
• Biomolecular nanosensors
• Field Emitters
• Photon Ballistic Waveguides
Nanowires do not occur spontaneously in nature and must be produced under controlled conditions. Synthesis methods for the production of nanowires include vapour deposition, suspension and Vapor-Liquid-Solid (VLS) synthesis methods.