discovered 02_2012

discovered 02.12 COLLABORATIONS WWW.Hzdr.DE // A round of applause for the TU Dresden: On Friday, June 15, the decision was made by the government and the federal states regarding the competition of excellence and the TU was able to score points in all aspects of its programs. Researchers at the Helmholtz-Zentrum Dresden-Rossendorf were also very pleased with these results, as they are participating in the two approved excellence clusters and the graduate school. The main activities are involved in the newly established excellence cluster cfAED (Center for Advancing Electronics Dresden) and the graduate school DIGS-BB (Dresden International Graduate School for Biomedicine and Bioengineering), which has been supported within the framework of the excellence initiative since 2006. _TEXT . Uta Bilow Translation . Sarah Gwillym-Margianto A success story: the excellence initiative In the excellence cluster cfAED everything revolves around microelectronics and beyond. Information and communications technology has developed at an unprecedented rate over the last few decades und has been at the impetus for innovations in the most varied fields of application, whether this be communication, entertainment, mobility or the world of business. Experts are concerned however that there is little potential remaining in terms of developing conventional electronics. Today’s information and communications technology is based on the so-called CMOS-semiconductor technology. The structures on a chip are already incredibly small and compressed, and the limits to what is actually physically possible will soon have been reached. Hence, researchers in the cluster of excellence cfAED push forward research on completely new technologies for the electronic information processing of the future and hopes are high that they will overcome the current limitations. Electronics with logic that can be reprogrammed “There are a whole range of materials that could be candidates in the future of electronics“, explains Artur Erbe from the Division of Scaling Phenomena at the HZDR. “This would include for example carbon nanotubes or nanowires made of silicon, which we are investigating more closely.“ Silicon nanowires are made from the same material as conventional components. Their potential, however, extends well beyond the conventional semiconductor technology. As demonstrated in seminal work by cfAED project partners at TUD’s Namlab facilities, these incredibly thin structures enable a logic that can be reprogrammed, explains the physicist: “A gate-electrode is used to switch between such nanowires. One can therefore switch spontaneously between a p- and an n-type transistor.“ Conventional silicon on the other hand is fixed to one type through its doping. The advantages of the nanowires are obvious: complex functionality can be achieved with considerably fewer components, providing brand new opportunities for software. The HZDR researchers have a lot of experience in reliably connecting such tiny wires individually using electron beam lithography. This is imperative, so that the properties of the nanowires can be calibrated with precision. In other experiments the scientists coated the wires on the surface to investigate what kind of effect this would have. Says Artur Erbe: “If we attach individual molecules to the surface, the conductivity changes as does the switching behavior of the wires.“ This effect can be used for gas sensors for example. Furthermore, it is possible to influence the behavior of the wire in a chemical way. Nanotubes purposefully arranged According to many experts, carbon in the form of nanotubes is yet another material that could play an important role in the future of microelectronics. Here scientists at the HZDR are primarily concentrating on purposefully arranging the nanotubes. “We are using defect engineering for this“, explains Artur Erbe. Many materials are not uniform, but exhibit grains, domains, or even atom-scale relaxations which structure the surface into small sub-units. The carbon nanotubes adsorb differently on defect-rich and perfect surface areas and can be enriched at defect sites. “Some of the defects can be written optically, i.e. they can literally be determined by light. Hence, we are able to determine with a precision of up to ten nanometers how the nanotubes are arranged“, says Erbe. To encourage the cooperation between the partners of the excellence cluster, a new research facility is slated to be built on the TU campus in the near future. As part of its inventory, the Rossendorf scientists will contribute equipment for etching as well as several measuring instruments.

discovered 02_2012

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