Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hybrid semiconductors show zero thermal expansion; could lead to hardier electronics and optoelectronics

20.12.2007
The fan in your computer is there to keep the microprocessor chip from heating to the point where its component materials start to expand, inducing cracks that interrupt the flow of electricity — and not incidentally, ruin the chip. Thermal expansion can also separate semiconducting materials from the substrate, reduce performance through changes in the electronic structure of the material or warp the delicate structures that emit laser light.

Recently published research by scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) and Argonne National Laboratory, and academic institutions has shed light on a semiconducting material with zero thermal expansion (ZTE). The research may play a role in the design of future generations of electronics and optoelectronics that can withstand a wide range of temperatures.

Traditional interests in ZTE materials have largely been in areas such as optics, heat-engine components and kitchenware. ZTE materials with applications in non-conventional areas such as electronics and optoelectronics are rare; most are glasses, which do not work well in electronics applications. The hybrid inorganic-organic semiconductor investigated in this work is a multifunctional semiconductor that has previously been shown to possess superior electronic and optical properties. The work also suggests an alternative route to designing materials with any desired positive or negative thermal expansion.

“It's a merger of inorganic and organic materials,” said Zahirul Islam, a physicist in Argonne's X-Ray Science Division, “which form a fully coherent, three-dimensionally ordered crystal. Normally inorganic and organic materials don't work very well together, but here they are working together to display these remarkable properties.”

The materials under study form alternating organic and inorganic layers that work together to produce these effects. One contracts while the other expands, and the net effect is zero.

“This work suggests a novel approach to design the thermal expansion — from positive to negative, including zero — in a nanoscopic scale by assembling nano-scale units in an ordered manner,” said principal investigator Yong Zhang of NREL. “The idea has only been demonstrated for tuning thermal expansion in one dimension and study was limited to one or two materials. Next, we would like to extend the idea to higher dimensions (i.e., ZTE in more than one dimension), and explore more inorganic-organic combinations.”

These hybrid materials hold promise for high-efficiency semiconductor lasers, ultrathin and flexible solar cells and light-emitting and detecting devices. It is possible to “dope” the materials (adding small amounts of other compounds) to form transparent conducting materials, Zhang said.

While chemical and thermal stability are two major problems for most hybrids, the hybrid nanostructures investigated in this work are found to be exceptionally stable in the air, even under the illumination of an ultraviolet laser.

“Not only do the crystal structures remain unchanged,” Zhang said, “but their electronic and optical properties remain after a few years of air exposure or upon heating to more than 200 degrees C, a feature attributed to the strong covalent bonding throughout the structure.”

This work involved multiple institutes with complementary strengths and capabilities. Scientists at NREL initiated and organized the project. The materials were synthesized by Jing Li's group at Rutgers University. Critical X-ray diffraction measurements to determine the ZTE effects were carried out at Argonne's Advanced Photon Source. Other key Argonne researchers are Yang Ren and Peter L. Lee. Theoretical modeling on the phonon (vibrational) spectrum, crucial to the understanding of the experimental findings, was performed by scientists at the University of Arkansas. Collaborators at the University of Colorado at Boulder also made important contributions to the work.

Argonne National Laboratory, a renowned R&D center, brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

Steve McGregor | EurekAlert!
Further information:
http://www.anl.gov

More articles from Physics and Astronomy:

nachricht Innovative LED High Power Light Source for UV
22.06.2017 | Omicron - Laserage Laserprodukte GmbH

nachricht Spin liquids − back to the roots
22.06.2017 | Universität Augsburg

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: 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)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

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

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>