Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Unusual nanoscale mound formation

Scanning force microscopy scan of a terraced mound of upright organic molecules. The terrace height corresponds to the molecule length. (©: G. Hlawacek, C. Teichert)
Scanning force microscopy scan of a terraced mound of upright organic molecules. The terrace height corresponds to the molecule length. (©: G. Hlawacek, C. Teichert)

Abstract:
Terrace-like elevations of just a few nanometres can form during production of organic thin films made from electrically conductive material. This phenomenon was previously only known from inorganic materials and is crucially important for future production of a new generation of semi-conductor components based on organic thin films. The data now published in the first July edition of SCIENCE was collated as part of a national research network funded by the Austrian Science Fund FWF.

Unusual nanoscale mound formation

Austria | Posted on July 9th, 2008

Inorganic semi-conductors have a simple construction and have made high-performance computers possible. In contrast, organic semi-conductors are complex but enable production of innovative electronic circuits, as vividly demonstrated by the first prototypes for roll-up screens. Yet these benefits of organic semi-conductors can only be fully harnessed when the response of their organic molecular layer - whose thinness is crucial in functional terms - is better understood. The national research network (NRN) "Interface controlled and functionalised organic thin films" of the Austrian Science Fund FWF is contributing to precisely this understanding.

Microscopic Height Measurement
In the latest issue of SCIENCE, a team from the NRN has now been able to show that organic molecules spread out on a carrier material in a previously unknown form to create thin electrically conductive films. As Prof. Christian Teichert from the Institute of Physics at the University of Leoben explains: "Totally surprising diffusion behaviour at step edges formed during film growth was observed on the films of the organic substance parahexaphenyl produced by solid state physicists from Graz University of Technology. The molecules here come into contact with a diffusion barrier, which leads to the other molecules piling up. Although a diffusion barrier of this nature is well known in inorganic, atomically structured films - it is called the Ehrlich-Schwoebel barrier in honour of its inventors - it had not previously been observed for organic materials."

The team in Leoben used scanning force microscopy to better understand this hitherto unknown behaviour of the organic molecules. This enabled precise measurement of the nano mounds at the step edges. Evaluation of the data thus obtained led to a further surprise. The shape of the nano elevations is strongly reminiscent of the terraced mounds encountered in mining. The team was struck by the fact that the terrace height of 2.6 nm almost exactly matches the length of a molecule of parahexaphenyl. The conclusion from this is that the molecules align themselves upright within a terrace.

However, it was also shown that the lower terraces are somewhat lower in height than those above. Project team member Dr. Gregor Hlawacek explains this phenomenon: "The data from the measurement allowed us to calculate the Ehrlich-Schwoebel barrier for this case. It also transpired that the molecules of the lower terraces are deposited at an angle. As a result, the terrace height here diminishes relative to the angle of inclination."

Energy-saving Measure at Nano Level
The measured values were used to perform computer simulations in the Chair of Atomistic Modelling and Design of Materials. These were not only able to confirm the experimental values for the diffusion barriers but also revealed that the parahexaphenyl molecules are bent in diffusion. This was surprising as bending requires expansion of the bonds in the molecule, which is in fact avoided owing to the energy required. However, in this way, the diffusing molecule can maintain bonds to neighbouring molecules more effectively than a rigid molecule, so that bending is overall the more energy-saving mechanism.

For the team from Leoben and Graz, these findings are extremely exciting as producing organic thin-film transistors requires closed films of such upright molecules. Improved understanding of the fundamental forces that bring this about will enable them to be manipulated and thus used in a controlled way. This NRN is therefore making a direct contribution to the future production of a new generation of semi-conductor components.

Original publication: Characterization of Step-Edge Barriers in Organic Thin-Film Growth, G. Hlawacek, P. Puschnig, A. Winkler, C. Ambrosch-Draxl & C. Teichert. Science (2008), 108-111.

####

About Austrian Science Fund (FWF)
The Austrian Science Fund (FWF) is Austria's central body for the promotion of basic research. It is equally committed to all branches of science and in all its activities is guided solely by the standards of the international scientific community.

For more information, please click here

Contacts:
Scientific Contact
Prof. Christian Teichert
University of Leoben
Institute of Physics
T + 43 / 3842 / 402 - 4663
E

Austrian Science Fund FWF
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Wien
Austria
T +43 / 1 / 505 67 40 - 8111
E

Copy Editing & Distribution
PR&D - Public Relations for Research & Education
Campus Vienna Biocenter 2
1030 Wien
Austria
T +43 / 1 / 505 70 44
E

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Engineers develop new materials for hydrogen storage April 15th, 2014

Nanocrystalline cellulose modified into an efficient viral inhibitor April 15th, 2014

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun ó even when itís not shining April 15th, 2014

Thin films

Industry Veteran Fergus Clarke Joins Picodeon as CEO: Appointment comes as Picodeon prepares for growth April 8th, 2014

Scalable CVD process for making 2-D molybdenum diselenide: Rice, NTU scientists unveil CVD production for coveted 2-D semiconductor April 8th, 2014

High-quality nanometric bilayers prepared by aqueous solutions March 26th, 2014

A new concept for manufacturing wrinkling patterns on hard-nano-film/soft-matter-substrate March 24th, 2014

Chip Technology

Scientists open door to better solar cells, superconductors and hard-drives: Research enhances understanding of materials interfaces April 14th, 2014

Obducat has launched a new generation of SINDREģ Nano Imprint production system April 11th, 2014

Scientists in Singapore develop novel ultra-fast electrical circuits using light-generated tunneling currents April 10th, 2014

Nanotech Business Review 2013-2014 April 9th, 2014

Discoveries

Nanocrystalline cellulose modified into an efficient viral inhibitor April 15th, 2014

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun ó even when itís not shining April 15th, 2014

Targeting cancer with a triple threat: MIT chemists design nanoparticles that can deliver three cancer drugs at a time April 15th, 2014

Announcements

Tiny particles could help verify goods: Chemical engineers hope smartphone-readable microparticles could crack down on counterfeiting April 15th, 2014

A molecular approach to solar power: Switchable material could harness the power of the sun ó even when itís not shining April 15th, 2014

Targeting cancer with a triple threat: MIT chemists design nanoparticles that can deliver three cancer drugs at a time April 15th, 2014

Biologists Develop Nanosensors to Visualize Movements and Distribution of Plant Stress Hormone April 15th, 2014

NanoNews-Digest
The latest news from around the world, FREE







  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE