Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanowires can now be controlled

23.12.2008
Nanoscience researchers at Lund University in Sweden have shown that they can control the growth and crystal structure of nanowires down to the single atom level.

How this can be done is described in an article to appear in the January issue of Nature Nanotechnology, with Philippe Caroff and Kimberly Dick as the main authors.

According to Professor Lars Samuelson, this is a breakthrough both in the development of nanowire growth, and in the understanding of the fundamental materials physics processes involved.

- The results achieved here establish our position in this area of science and technology and give our ambitions an increased credibility, he says. The useful applications will not be far away.

It has been known for a long time that most semiconductor materials used in nanowires, including the very interesting material Indium Arsenide (InAs) studied here, are affected by irregularities in the layer-by-layer stacking sequence. These affect the electronic and optical properties in uncontrolled ways, and are therefore undesirable.

But now Philippe Caroff and Kimberly Dick have shown that it is possible to control these variations in great detail, which can be used for the development of new functions in nanowires.

It is now possible not only to fabricate perfect, defect-free nanowires, but also to switch freely between different crystal types along the length of a single nanowire, to produce a, so-called, superlattice, but still using only one chemical compound (InAs).

- Two of the key parameters needed to control the crystal structure are nanowire diameter and the temperature at which they are fabricated. But there are in total at least 10-12 different parameters that must be controlled when producing the nanowires, says Kimberly Dick.

Although this result has been demonstrated primarily for the binary compound InAs, it is believed that the mechanisms controlling the nanowire structure can be generally applied to related semiconductor materials used in nanotechnology.

With this technique it is also possible to grow highly regular nanowires with a perfect periodic facetted character.

Electron microscopy images show that the arrangement of atoms in the nanowire crystal exactly matches theoretical simulations. The electronic and optical properties of these wires have not been investigated yet but will be in the focus of theoretical as well as experimental studies.

The nanowires in this study had a typical diameter of 10-100 nanometers (one nanometer is one-millionth of one millimeter) and length of a few micrometers (one-thousandth of one millimeter).

The wires are produced by "baking" in an oven with a supply material in gas form, and grow from small microscopic gold "seeds". Kimberly Dick defended a PhD thesis last year containing many electron microscopy images of similar nanowires.

The researchers work within the Nanometer Structure Consortium (nmC) at Lund University to also find commercial applications for these nanowires in electronics and opto-electronics, such as for light-emission and solar cell applications.

Lars Samuelsson could be contacted at
e-mail: Lars.Samuelson@ftf.lth.se or +46-70 317 7679.
Pressofficer Mats Nygren Mats.Nygren@kansli.lth.se or +46-708 220187
The original article "Controlled polytypic and twin-plane superlattices in III-V nanowires" written by the Lund University scientists P Caroff, K A Dick, J Johansson, M E Messing, K Deppert and L Samuelson is available at www.nature.com/naturenanotechnology.

It is also reviewed in an article in Semiconductor Today: www.semiconductor-today.com/news_items/2008/DEC/LUNDUNIVERSITY_021208.htm

Mats Nygren | idw
Further information:
http://www.vr.se
http://www.lth.se/formedia/nanofigurer/
http://www.semiconductor-today.com/news_items/2008/DEC/LUNDUNIVERSITY_021208.htm

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>