Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New technique for measuring nanostructures

26.08.2014

Bringing two electrical insulators together to create an electrical superconductor: Anyone wishing to analyze such phenomena in nanostructures will soon come up against metrological limitations – unless a new method is used that Würzburg physicists have helped to develop.

Modern electronic devices contain components such as transistors and diodes consisting of semiconductor layers made of silicon, germanium or gallium, and arsenic. Semiconductors made from these chemical elements have relatively simple properties that have been well characterized scientifically.


X-ray interference pattern measured while studying complex nano-layer structures. The sketch inserted illustrates the path of the x-ray beam relative to the surface of the sample.

(Graphic: Sebastian Macke)

Likewise, the possible applications for such layer structures in memory modules and microprocessors are also simple: “The primary objectives of technological improvements are further miniaturization, increasing component density, and greater speed,” says physics professor Vladimir Hinkov from the University of Würzburg.

Elements that reveal interesting phenomena

On the other hand, science expects to unearth entirely new possibilities with components that contain manganese, nickel, titanium, and other elements from the so-called subgroups. “These metals have electron clouds that enable more complex bonds and electron configurations.

This leads to physical phenomena that are unknown in semiconductors,” says Hinkov. As examples of such phenomena he mentions tremendous magnetoresistance and various magnetic orders, all of which occur in oxides of these metals.

Even more interesting application possibilities are opened up when these oxides are placed on top of each other in ultra-thin layers, some only a few atoms thick.

For example, electrical resistance completely disappears at the interface between strontium titanate (SrTiO3) and lanthanum aluminate (LaAlO3) – despite the fact that both materials in themselves have very high electrical resistance they become a superconductor at their shared interface. So, it is no wonder that such nanostructures are the subject of intensive research.

Why the analysis of nanostructures is complicated

Chemical composition, magnetic order, distribution of electrons in the electron clouds: “Recording these properties sounds like an easy task, but in reality it is extremely complicated and conventional measurement methods can be used in very few cases,” says the Würzburg professor of physics. One reason for this is that the phenomena of interest occur in the nanocosmos, on length scales of just a few nanometers.

Of course, there are measurement methods with nanometer resolution, but these have disadvantages. One example is popular Scanning Transmission Electron Microscopy (STEM). Here, thin slices are removed from a nanostructure and scanned with an electron beam. The sample therefore has to be destroyed for the test – but doing so may change the properties that you actually want to analyze.

What the newly developed measurement method can do

With Vladimir Hinkov as the coordinator, a team of scientists from Germany, Canada, and the USA has now developed a promising new measurement method and presented it in the journal “Advanced Materials”. It works without destroying anything, offers a nanometer resolution, identifies the chemical elements involved, and is able to determine both the magnetic order and the electron distribution. Tiny traces of elements hidden deep in the nanostructure can also be identified using this method. Chemical profiles can be determined even in structures made from many elements and with complex layering.

The method, an enhancement of resonant x-ray reflectometry, is based on the scattering of x-rays with a wavelength of a few nanometers at the interfaces of the layer structure: The various scattered partial beams are then superimposed and measured. The measurements are processed accordingly to deliver an image of the structure with depth resolution. In this approach, the method resembles optical holography, which is used to generate images with spatial resolution.

Why success was dependent on many specialists

“An undertaking of this magnitude was only possible with the involvement of colleagues from many different disciplines,” says Hinkov. First you need x-ray light of such high intensity and quality as can only be generated using synchrotrons. The measurements are taken using highly specialized instruments, which the researchers set up on the synchrotron itself.

In addition, nanostructures of the highest quality are required in order to refine and test the method. The measurement data are analyzed using specially developed software and, finally, the results need to be discussed with theoreticians to arrive at a better understanding of the phenomena.

The next steps in the research

“We have been working intensively on this project for several years, and now our patience has really paid off,” says the Würzburg physicist happily. While it is true that the layer structures examined are not yet components for applications, the materials used are technologically relevant and the next development stages are clear: “Research into structures with interesting magnetic and electronic properties and, in the not too distant future, the design of elements with customized physical and technological properties,” explains Hinkov. Switchable magnetism, superconductivity, and novel sensors are some of the applications that offer promising possibilities here.

“Element Specific Monolayer Depth Profiling”, Sebastian Macke, Abdullah Radi, Jorge E. Hamann-Borrero, Martin Bluschke, Sebastian Brück, Eberhard Goering, Ronny Sutarto, Feizhou He, Georg Cristiani, Meng Wu, Eva Benckiser, Hanns-Ulrich Habermeier, Gennady Logvenov, Nicolas Gauquelin, Gianluigi A. Botton, Adam P. Kajdos, Susanne Stemmer, Georg A. Sawatzky, Maurits W. Haverkort, Bernhard Keimer, and Vladimir Hinkov. Advanced Materials, August 8, 2014, DOI: 10.1002/adma.201402028

Contact

Prof. Dr. Vladimir Hinkov, Department of Experimental Physics IV, University of Würzburg, T +49 (0)931 31-84481, hinkov@physik.uni-wuerzburg.de

Robert Emmerich | Julius-Maximilians-Universität Würzburg
Further information:
http://www.uni-wuerzburg.de

More articles from Physics and Astronomy:

nachricht Hubble observes one-of-a-kind star nicknamed 'Nasty'
22.05.2015 | NASA/Goddard Space Flight Center

nachricht Basel Physicists Develop Efficient Method of Signal Transmission from Nanocomponents
22.05.2015 | Universität Basel

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: Basel Physicists Develop Efficient Method of Signal Transmission from Nanocomponents

Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.

Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...

Im Focus: IoT-based Advanced Automobile Parking Navigation System

Development and implementation of an advanced automobile parking navigation platform for parking services

To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...

Im Focus: First electrical car ferry in the world in operation in Norway now

  • Siemens delivers electric propulsion system and charging stations with lithium-ion batteries charged from hydro power
  • Ferry only uses 150 kilowatt hours (kWh) per route and reduces cost of fuel by 60 percent
  • Milestone on the road to operating emission-free ferries

The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...

Im Focus: Into the ice – RV Polarstern opens the arctic season by setting course for Spitsbergen

On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.

RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...

Im Focus: Gel filled with nanosponges cleans up MRSA infections

Nanoengineers at the University of California, San Diego developed a gel filled with toxin-absorbing nanosponges that could lead to an effective treatment for skin and wound infections caused by MRSA (methicillin-resistant Staphylococcus aureus), an antibiotic-resistant bacteria. This "nanosponge-hydrogel" minimized the growth of skin lesions on mice infected with MRSA - without the use of antibiotics. The researchers recently published their findings online in Advanced Materials.

To make the nanosponge-hydrogel, the team mixed nanosponges, which are nanoparticles that absorb dangerous toxins produced by MRSA, E. coli and other...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International symposium: trends in spatial analysis and modelling for a more sustainable land use

20.05.2015 | Event News

15th conference of the International Association of Colloid and Interface Scientists

18.05.2015 | Event News

EHFG 2015: Securing health in Europe. Balancing priorities, sharing responsibilities

12.05.2015 | Event News

 
Latest News

Mesoporous Particles for the Development of Drug Delivery System Safe to Human Bodies

22.05.2015 | Materials Sciences

Computing at the Speed of Light

22.05.2015 | Information Technology

Development of Gold Nanoparticles That Control Osteogenic Differentiation of Stem Cells

22.05.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>