However, physicists of the University of Würzburg are paving the way for them: In the American scientific journal "Science", the researchers now present a semiconductor that transmits electric current without heating up in the process.
This new type of semiconductor consists of mercury telluride and mercury cadmium telluride. In a sophisticated procedure, the Würzburg physicists apply these two materials to penny-sized crystal wafers in alternate ultra-thin layers. "The individual layers are only seven to ten nanometers thin," says Professor Laurens Molenkamp. In other words, inconceivably fine: A nanometer is one millionth of a millimeter.
Tiny wire fabricated
In order to analyze the conductivity of the layered material, the physicists structured its surface, using lithographic patterning methods. They sort of created tiny wires in a specific pattern, e.g. an H-shaped structure.
"The material was expected to become an insulator under certain conditions - at very low temperatures, for instance. All conventional semiconductors exhibit this behavior," explains Professor Hartmut Buhmann, who works in Molenkamp's team.
Material reacted in an unexpected way
The physicists were in for a surprise, when the material behaved differently: The electrons concentrated at the edges of the H-shaped structure. In addition to this, they were freely moveable there - without any resistance and thus without dissipating heat. According to the physicists, this characteristic is based wholly on the materials and the way they are layered. The form of the structure - whether H or X - is irrelevant.
Not yet ready for application
This new type of semiconductor is not yet ready for real-world applications, though. The effect described above occurs only at extremely low temperatures below minus 170 degrees Celsius. Therefore, the Würzburg researchers now intend to develop other materials, which produce the same effect at significantly higher temperatures.
"We are going to use bismuth compounds for this purpose," says Laurens Molenkamp. However, they first have to work out a procedure allowing them to stack these materials as well in neat wafer-thin layers.
To stay cool is important for computers
When computers are processing, they heat up. But if temperatures get too high, the function of computer chips is adversely affected, which means they need cooling. The cooling is provided by fans on board the PC or by air conditioning systems in large computer rooms. Some high-performance computers of today are already equipped with water-cooling systems.
So heat is a factor that considerably limits the development of faster computers. This is because more and more transistors, working ever faster, have to be tightly packed on the chips in order to reach higher levels of performance. "Consequently, a higher amount of electric current passes through the chips, inducing an increased heat build-up in the components," explains Hartmut Buhmann. Hence, the advent of components that conduct electric current without generating heat would be likely to give a big push to the evolution of computers.
Nonlocal Transport in the Quantum Spin Hall State, Andreas Roth, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp, Joseph Maciejko, Xiao-Liang Qi, Shou-Cheng Zhang, Science, 17. Juli 2009, Vol. 325, no. 5938, pp. 294-297, DOI: 10.1126/science.1174736
Prof. Dr. Laurens Molenkamp, Chair of Experimental Physics III, University of Würzburg, phone ++49 (931) 888-4925, firstname.lastname@example.org
Prof. Dr. Hartmut Buhmann, phone ++49 (931) 888-5778, email@example.com
Robert Emmerich | idw
Drones that drive
27.06.2017 | Massachusetts Institute of Technology, CSAIL
Ahead of the Curve
27.06.2017 | Institute of Science and Technology Austria
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...
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...
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...
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...
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)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy