Major advance in understanding how nanowires form

Mar 25, 2011
High resolution image of the crystal structure of an InAs nanowire photographed with an electronmicroscope. The smallest distance between the Indium and Arsenic atoms seen in the picture (illustrated with green and gray), is 15 millionths of a millimeter. The nanowire is grown in the direction of the arrow. During growth the crystal structure of the nanowire changes from being hexagonal (WZ) to cubic (ZB). From the crystal orientation seen in the image, the hexagonal structure is characterized by the direction from the Indium to Arsenic atoms changes from layer to layer, while the direction of the cubic structure is always the same.

New insights into why and how nanowires take the form they do will have profound implications for the development of future electronic components. PhD student Peter Krogstrup from the Nano-Science Center at the Niels Bohr Institute, University of Copenhagen is behind the sensational new theoretical model, which is developed in collaboration with researchers from CINAM-CNRS in Marseille. The results have been published in the scientific magazine, Physical Review Letters.

One of the most important components in future will likely be based on , which are smaller than the wavelength of the light our eyes can detect. Nanowires, which are extremely thin nanocrystal wires, are predicted to have a predominant role in these technologies because of their unique electrical and . Researchers around the world have been working for years to improve the properties of these nanowires.

With his research, PhD student Peter Krogstrup at the Niels Bohr Institute, University of Copenhagen has laid the foundations for a greater understanding of nanowires. With that comes the potential for improving their performance, which will bring the research closer to being applied in the development of and computers. In the latest edition of he describes how, under certain conditions, nanowires form a crystal structure that really should not be possible, seen from an energy perspective.

"Crystals will always try to take the form in which their internal energy is as little as possible. It is a basic law of physics and according to it these nanowires should have a cubic crystal structure, but we almost always see that a large part of the structure is hexagonal", explains Peter Krogstrup, who has been working with the theory in recent years.

Catalyst particle shape is the key

In order to explain why and when these crystals become hexagonal, Peter Krogstrup has, as part of his doctoral dissertation, examined the shape of the catalyst particle (a little nano-droplet), which controls the growth of the nanowires. It appears that the shape of the droplet depends on the amount of atoms from group 3 in the periodic system, which make up half of the atoms in the nanowire crystal. The other half, atoms from group 5 in the periodic system, are absorbed by the drop and hence the atoms organize themselves into a lattice, and the nanowire crystal will grow.

"We have shown that it is the shape of the droplet, which determines what kind of crystal structure the nanowires obtain and with this knowledge it will be easier to improve the properties of the nanowires", explains Peter Krogstrup and continues:

"The has an enormous influence on the electrical and optical properties of the nanowires and you would typically want them to have a certain structure, either cubic or hexagonal. The better nanowires we can make the better electronic components we can make to the benefit of us all", says Peter Krogstrup, whose research is conducted in collaboration with the firm SunFlake A/S, which is located at the Nano-Science Center at the Niels Bohr Institute, University of Copenhagen. The company is working to develop solar cells of the future based on nanowires.

Explore further: In-situ nanoindentation study of phase transformation in magnetic shape memory alloys

More information: prl.aps.org/abstract/PRL/v106/i12/e125505

Provided by Niels Bohr Institute

5 /5 (2 votes)

Related Stories

Great potential with new ultra-clean nanowires

Nov 09, 2010

New ultra-clean nanowires produced at the Nano-Science Center, University of Copenhagen will have a central role in the development of new high-efficiency solar cells and electronics on a nanometer scale. ...

Danish nanowires have great potential

Nov 02, 2009

Danish nanophysicists have developed a new method for manufacturing the cornerstone of nanotechnology research - nanowires. The discovery has great potential for the development of nanoelectronics and highly ...

Chemists measure copper levels in zinc oxide nanowires

Feb 19, 2008

Chemists at the National Institute of Standards and Technology have been the first to measure significant amounts of copper incorporated into zinc oxide (ZnO) nanowires during fabrication. The issue is important ...

Recommended for you

'Exotic' material is like a switch when super thin

Apr 18, 2014

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

User comments : 0

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...