How do nanowires work

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Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Download PDF. Abstract The synthesis and the characterisation of silicon nanowires SiNWs have recently attracted great attention due to their potential applications in electronics and photonics.

Introduction Semiconductor nanowires have attracted great attention owing to their submicron ultimate feature size, to the expected original electrical and optical properties and the potential applications in the field of nanoelectronics, high-speed field effect transistors, bio- and chemical sensors, and light-emitting devices with low power consumption [ 1 — 8 ].

Fabrication of nanowires Due to the highly importance and a large utilization of silicon nanowire we will focus on this type of nanowire. Physical evaporation of a silicon powder The first synthesis of silicon nanowires by evaporation techniques was proposed by Yu and Co.

Full size image. Scheme illustrated the vapor liquid solid mechanism. Table 1 Summary of experimental conditions for the synthesis of silicon nanowires by laser ablation [ 33 ] Full size table. Nanowires characterization The geometrical and structural factor plays an important role in determining the electrical and optical properties.

The electronic We have reviewed the different methods of synthesis of nanowires and characterization techniques, the ability to control the size, chemical composition, physical and electronic properties of nanowires. Table 2 Comparison between the carrier mobility of semiconductor nanowires and in the bulk [ 47 ] Full size table.

Conclusion In this review, we have an update on the various techniques of synthesis of semiconductor nanowires with special attention given to silicon nanowires.

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Let's assume you have found an exceptionally fine hair with a width of 60 micrometers. A micrometer is 1, nanometers, so you would have to cut that hair at least 60, times lengthwise to make a strand one nanometer thick. Depending on what it's made from, a nanowire can have the properties of an insulator, a semiconductor or a metal. Insulators won't carry an electric charge, while metals carry electric charges very well. Semiconductors fall between the two, carrying a charge under the right conditions.

By arranging semiconductor wires in the proper configuration, engineers can create transistors, which either acts as a switch or an amplifier. Some interesting -- and counterintuitive -- properties nanowires possess are due to the small scale.

When you work with objects that are at the nanoscale or smaller, you begin to enter the realm of quantum mechanics. Quantum mechanics can be confusing even to experts in the field, and very often it defies classical physics also known as Newtonian physics. For example, normally an electron can't pass through an insulator.

If the insulator is thin enough, though, the electron can pass from one side of the insulator to the other. It's called electron tunneling , but the name doesn't really give you an idea of how weird this process can be. The electron passes from one side of the insulator to the other without actually penetrating the insulator itself or occupying the space inside the insulator. You might say it teleports from one side to the other. You can prevent electron tunneling by using thicker layers of insulator since electrons can only travel across very small distances.

Another interesting property is that some nanowires are ballistic conductors. In normal conductors, electrons collide with the atoms in the conductor material.

This slows down the electrons as they travel and creates heat as a byproduct. In ballistic conductors, the electrons can travel through the conductor without collisions. Nanowires could conduct electricity efficiently without the byproduct of intense heat. At the nanoscale, elements can display very different properties than what we've come to expect.

For example, in bulk, gold has a melting point of more than 1, degrees Celsius. By reducing bulk gold to the size of nanoparticles, you decrease its melting point, because when you reduce any particle to the nanoscale, there's a significant increase in the surface-to-volume ratio.

Also, at the nanoscale, gold behaves like a semiconductor, but in bulk form it's a conductor. Other elements behave strangely at the nanoscale as well. In bulk, aluminum isn't magnetic , but very small clusters of aluminum atoms are magnetic. The elemental properties we're familiar with in our everyday experience -- and the ways we expect them to behave -- may not apply when we reduce those elements down to the size of a nanometer. We're still learning about the different properties of various elements at the nanoscale.

Some elements, like silicon, don't change much at the nanoscale level. This makes them ideal for transistors and other applications. Others are still mysterious, and may display properties that we can't predict right now. Nanowires are just one exciting structure engineers and scientists are exploring at the nanoscale. Two other important nanoscale objects are carbon nanotubes and quantum dots. A carbon nanotube is a cylindrical structure that looks like a rolled up sheet of graphite.

Its properties depend on how you roll the graphite into the cylinder -- by rolling the carbon atoms one way, you can create a semiconductor.

But rolling them another way can make a material times stronger than steel. Quantum dots are collections of atoms that together act like one giant atom -- though by giant we're still talking the nanoscale. Quantum dots are semiconductors. Nanoscience specialists talk about two different approaches to building things in the nanoscale: the top-down approach and the bottom-up approach.

A top-down approach essentially means that you take a bulk amount of the material you plan on using for nanowires and carve away until you are down to the right size.

A bottom-up approach is an assembly process where smaller particles join to make a larger structure. Although we can build nanowires using either approach, no one has found a way to make mass production feasible. Right now, scientists and engineers would have to spend a lot of time to make a fraction of the number of nanowires they would need for a microprocessor chip. Nanotechnology could be seen as engineering of functional systems at the atomic scale, which illustrates the growth of nanowires, where different atomic layers are stacked on top of each other.

In the study Interface Dynamics and Crystal Phase Switching in GaAs Nanowires, the researchers were able to monitor in real time where each new atomic layer is placed in a growing nanowire, and explain why they place themselves where they do.

The study shows that it is possible to control the position of each new atomic layer, and was conducted in collaboration with researchers at the IBM T. A nanowire is an extremely thin wire with a diameter equal to one thousandth of a human hair. They are made out of many different materials, for example metals such as silver and nickel, semiconductor materials such as silicon and gallium arsenide, and insulating material such as silicon oxide. Nanowires are useful because they enable the formation of complex structures with many chemical compounds, and sometimes different atomic arrangements.

Nanowires are usually made out of single crystals, and the specific atomic arrangement is what determines the structure of the crystal. Every new type of complicated structure -- whether it be a combination of different materials or a new way of joining atoms together -- involve new properties and thereby different applications in areas such as electronics and lighting.

Materials provided by Lund University. Note: Content may be edited for style and length. Researchers at University of Massachusetts Amherst have developed protein nanowires that produce electric current when exposed to water vapor in air. Researchers at MIT have developed a solar cell using graphene coated with zinc oxide nanowires. The researchers believe that this method will allow the production of low cost flexible solar cells at high enough efficiency to be competive.

Researchers at Nagoya University are developing a nanowire based sensor to detect indicators of bladder and prostate cancer in urine samples. Researchers at NTU Singapore are using manganese dioxide nanowires to develop flexible capacitors. The idea is to have the capacitors in fabric to provide energy storage for wearable electronics. Sensors powered by electricity generated by piezoelectric zinc oxide nanowires. This could allow small, self contained, sensors powered by mechanical energy such as tides or wind.

Researchers are using a method called Aerotaxy to grow semiconducting nanowires on gold nanoparticles.