Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Surprise at the nanoscale: Silicon atoms jump after contact with metal

28.10.2015

Max Planck researchers from Stuttgart reveal unknown behaviour of semi-conductors at the nanoscale

Silicon is presently the most proper ingredient for microelectronic devices: it serves as basic material for all current computer chips. According to the increasing importance of electronic set-ups, the term “Silicon Age” is widely-used nowadays.


Semiconductor atoms (as silicon and germanium atoms) get influenced by metal (as aluminium) at the nanoscale and change their position through atomic jumps, even at temperatures as low as -190 degree celsius.

© Dr. Zumin Wang, MPI-IS Stuttgart

Further, the nickname Silicon Valley, representing the high-tech region in California, indi-cates the enormous importance of silicon for the semi-conductor and computer industry.

Crystalline silicon has also been widely used for the production of TFT-flatscreens and is, furthermore, a fundamental basic material for the assembling of photovoltaic cells.

A further semiconductor is germanium, which initially was the leading material in (micro) electronics, until it was replaced by silicon. Only few years ago, researchers discovered that monolayers of germanium conduct electrons up to 10 times faster than silicon. For this reason, germanium could catch up as semi-conductor again.

Silicon and germanium are both quite heat resistant and melt only at temperatures higher than 900 degree Celsius. At the solid state, the atoms are positioned within a regularly or-dered crystal lattice and can only vibrate slightly at their respective locations. With increas-ing temperature, the vibrations intensify and even “jumps“ to different sites in the solid occur. At room temperature these kind of atomic jumps are practically impossible.

Scientists led by Prof. Dr. Ir. Eric Jan Mittemeijer, Director at the Max Planck Institute for Intelligent Systems in Stuttgart, have recently discovered that atomic jumps occur in silicon and germanium even at very low temperature of minus 190 degree Celsius, if the thin layer of only 1 nanometer (millionth millimeter) gets in contact with metal, e.g. alu-minium.

The researcher Dr. Zumin Wang reports: „We tried to prepare artificial sandwiches com-posed of a very thin, 1-nm silicon or germanium film between two aluminium layers at minus 190 degree celsius. During this process we figured out that germanium or silicon always moved to the top surface of the aluminium. It was not possible to prepare such sandwiches. First, we found this “behavior” quite annoying, but soon we recognized that we had made a very surprising observation.”

While using X-ray photoelectron spectroscopy, the scientists found out that the bonding characteristics within germanium- and silicon atoms become strongly influenced when they get in touch with metals at thin-film set-ups. As a consequence, the semi-conductor atoms become able to “jump” more frequently. Because of these jumps, the atoms get mobile and change their position: they jump to the top surface of the aluminium. The metal influ-ences this mobility and has to be as close as half a nanometer.

Dr. Wang states: “This observation could become even more important since assembly parts for computers made of semi-conductor material shrink increasingly. Currently they are already as small as 10 to 40 nanometer, which means that at slightly smaller scale, mixing effects due to atomic jumps may arise. Secondly, the discovered process has impact on the preparation of thin film systems involving heat-sensitive materials, since the semi-conductor can become mobile even at very low temperature.”

Weitere Informationen:

http://www.is.mpg.de/mittemeijer

Annette Stumpf | Max-Planck-Institut für Intelligente Systeme

More articles from Materials Sciences:

nachricht The stacked colour sensor
16.11.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures
16.11.2017 | Karlsruher Institut für Technologie (KIT)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>