Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electronic charge distribution on the atomic scale

10.04.2015

Physicists tackle long-standing question using novel experimental approach

Scientists from the University of Göttingen and the Jülich Research Centre have made an important step towards a deeper understanding of metal-semiconductor interfaces. By means of a novel experimental approach the researchers investigated the distribution of the electronic charge at these interfaces on the atomic scale. Their results were published in the journal Physical Review Letters and highlighted as “Editors’ suggestion”.


Novel experiment on metal-semiconductor interfaces: A very sharp metal tip (red) is scanned across the iron/gallium arsenide interface

Universität Göttingen

In every electronic semiconductor device the interfaces between two different materials play a crucial role. In this context, the atomic and electronic structure of metal-semiconductor interfaces is of fundamental im-portance.

For the development and the design of novel nanometer-sized devices, a basic understanding of these interfaces is of central interest. However, up until now, no commonly accepted model that describes metal-semiconductor interfaces in their entirety existed. This is also due to the fact that scientists did not have an adequate experimental approach to investigate the atomic structure of these interfaces.

Now scientists in Göttingen and Jülich investigated the technologically interesting iron/gallium arsenide inter-face using a scanning tunneling microscope developed in Göttingen. “By scanning a very sharp metal tip across the interface we were able to simultaneously map its structure and its electronic properties on the atomic scale,” explains doctoral candidate Tim Iffländer from Göttingen University’s IV. Physical Institute.

“In combination with theoretical calculations from the colleagues in Jülich we found out that the electronic barrier between metal and semiconductor, on the one hand, is dominated by charges from the metal tailing into the semiconductor and, on the other hand, essentially depends on the chemical bonds between metal and semiconductor as well.”

“The high level of agreement between measured and calculated charge distribution at the interface demon-strates that our experimental approach is particularly well-suited to study the electronic properties of metal-semiconductor interfaces on the atomic scale,” adds Dr. Martin Wenderoth, head of the research group. “This allows us to check the relevance of several theoretical models.

Moreover, our experiment serves as starting point for further studies addressing the influence of defects and the detailed atomic structure at the interface on the electronic properties of metal-semiconductor contacts.”

Original publication: T. Iffländer et al. Local Density of States at Metal-Semiconductor Interfaces: An Atomic Scale Study. Phys. Rev. Lett. 114, 146804 (2015). Doi: 10.1103/PhysRevLett.114.146804 .

Contact:
Dr. Martin Wenderoth
University of Göttingen
Faculty of Physics – IV. Physical Institute
Friedrich-Hund-Platz 1, 37077 Göttingen
Phone +49 551 39-9367 or -4536
Email: wenderoth@ph4.physik.uni-goettingen.de
Web: www.uni-goettingen.de/en/500611.html 

Romas Bielke | idw - Informationsdienst Wissenschaft

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: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Fraunhofer ISE Pushes World Record for Multicrystalline Silicon Solar Cells to 22.3 Percent

25.09.2017 | Power and Electrical Engineering

Usher syndrome: Gene therapy restores hearing and balance

25.09.2017 | Health and Medicine

An international team of physicists a coherent amplification effect in laser excited dielectrics

25.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>