- Also called:
- quantum wire
- Related Topics:
- nanotechnology
- wire
nanowire
nanowire, thin wire, generally having a diameter less than or equal to 100 nanometers (nm; 1 nm = 1 × 10−9 meter). Nanowires are one-dimensional (1D) nanostructures, defined as having two dimensions in the nanoscale range and one dimension beyond that range; other examples of nanostructures include nanotubes and nanorods. The high length-to-diameter ratio of nanowires gives them unique electrical, optical, magnetic, and mechanical properties. Because nanowires have such small dimensions, they also display quantum mechanical phenomena (behaviors shown by matter and light at the atomic and subatomic scale). For this reason, nanowires are also referred to as quantum wires.
The first nanoscale quantum-well wire (a thinly layered semiconductor structure) was developed in 1987 by scientists at Bell Laboratories. In 1991 Belgian engineer Jean-Pierre Colinge developed a more refined nanowire. Since then nanowires have been investigated for possible applications in many fields, including optics, electronics, and genetics.
Fabrication and properties
Nanowires can be made from a wide variety of materials, including silicon, germanium, carbon, and various conductive metals, such as gold and copper. Scientists have explored multiple methods to synthesize nanowires, and each approach significantly affects the size and morphology of the material. Moreover, nanowire properties can be considerably altered by regulating their size, shape, and growth direction, broadening their applications.
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Nanowires have a high surface-to-volume ratio, which implies that a larger number of atoms are located on their surface, rather than within the wire, which drastically enhances their chemical reactivity and physical characteristics. Such features make nanowires viable candidates for use in sensors, where surface interactions play a dominant role. Other advantageous properties of nanowires include their low defect density, tunable electrical conductivity, and large optical output. Metallic nanowires exhibit high electrical conductivity, owing to the ballistic transport of electrons—a nanoscale phenomenon that enables electrons to move without resistance, thereby escalating overall conductivity. This property has led to important breakthroughs in computer science. For example, the development of an optical photonic switch using specialized cadmium sulfide nanowires that allow photons to pass through the wire and act as binary signals (i.e., 0 and 1) has the potential to greatly enhance computer speed.
Applications
Nanowires have diverse applications and are used commercially in optoelectronics, photovoltaics, biotechnology, and electronics. In electronics, nanowires have garnered enormous interest as the building blocks of new devices. For instance, researchers have attempted to reduce the size of existing transistors by using nanowire arrays, which can help overcome the physical limits of silicon transistors. Furthermore, metallic nanowires are considered promising candidates for use as transparent electrodes in display technologies. Semiconducting nanowires with tailored optical properties can be used in optoelectronic devices, such as ultraviolet lasers and waveguides, to manipulate and confine light at the nanoscale. Nanowires have also been shown to improve the optical absorption and efficiency in photovoltaic devices, which convert light into electricity.
The 2000s witnessed a significant leap in research related to applications of nanowires in biotechnology, especially in biomedical sensors, drug delivery, genetics, and biodetection. In genetics, researchers have used nanowires to create artificial protein-coding DNA. Such nanowires are formed using amino acids, which are the building blocks of proteins, and DNA. The technology could be used to facilitate the creation or production of proteins, thereby advancing protein research and potentially leading to advances in therapeutic applications, such as for the replacement or repair of dysfunctional proteins.