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Silicon at the breaking point could be basis for efficient transistors
Stretching a layer of silicon can build up internal mechanical strain which can considerably improve its electronic properties. With strained silicon, one can, for example, build faster and less power-consuming microprocessors.
Researchers at the Paul Scherrer Institute in Germany and the ETH Zurich have developed a method which allows them to produce 30-nm-thick highly strained wires in a silicon layer. This strain is the highest that has ever been observed in a material which can serve as the basis for electronic components. The aim is to produce high-performance and low-power transistors for microprocessors based on such wires.
As a starting point, the method uses a substrate with a silicon layer that is already under low strain. By selectively etching away the surrounding material, a thin wire is produced in the silicon layer which hangs like a tiny bridge over a gorge, with the highest strain concentrated at its narrowest point. The researchers report their results in the latest issue of the online journal Nature Communications.
There are limited possibilities for increasing the efficiency of microprocessors based on silicon technology by decreasing the size of individual building elements. But there are other promising ways, which are to some extent already used by industry, such as stretching or compressing silicon, thereby creating mechanical tension that helps to improve the electronic properties of the material. For example, tension in the correct direction significantly increases the mobility of electrons, which makes transistors much faster switching elements.
"There is actually no magic behind building up tension in a wire—you just have to pull strongly on both ends," explains Hans Sigg of the Laboratory for Micro- and Nanotechnology at the Paul Scherrer Institute. "The challenge is to implement such a wire in a stressed state into an electronic component."
30-nm–wide silicon bridge
Researchers at the Paul Scherrer Institute have now developed a method to create silicon wires which are tightly connected to their surrounding material and are under a tension which is more than twice as high as that used in contemporary components. As the initial material, they have used an industrially produced substrate with a slightly stressed silicon layer fixed onto a buried silicon oxide layer.
"It was important for us to show that our method is compatible with the fabrication methods and materials of industry," says Sigg.
"You can imagine the material as being pulled in all directions before it is attached to the oxide sublayer," explains Renato Minamisawa from the Paul Scherrer Institute, who conducted the experiments along with Martin Süess from ETH Zürich. "The substrate then holds the layer in place so that it cannot contract anymore."
In the process, cleverly chosen parts of the silicon layer and the oxide sublayer are removed by the respective etchants, to create a thin wire from the silicon layer—30 nm wide and 15 nm thick—that is attached to the rest of the material only at its endpoints. The method is exemplary for the possibilities of modern nanotechnology. In this way, thousands of such wires can be accurately produced in a well-defined stressed state. Thus the method is very reliable.
"And it is even scalable, meaning that the wires can be fabricated as small as you want," Sigg points out.
Faster transistors through high stresses
"Since all the force which was distributed over a larger area before the etching now has to concentrate in the wire, a high tension is created within it," says Minamisawa, "the strongest tension ever generated in silicon; probably even the strongest obtainable before the material breaks."
Raman spectroscopy and computer simulation were conducted in the Laboratory for Nanometallurgy under Ralph Spolenak at the ETH, in order to measure the stress distribution in detail. In the future, such wires will also be studied at the Swiss Light Source (SLS) at the Paul Scherrer Institute. The objective of such experiments will especially be to determine how much the electronic properties of the material have changed.
The ultimate goal would be to use these silicon nanowires as fast transistors within microprocessors. To achieve this, the researchers will now investigate, with partners, how to embed these wires in a transistor structure. For that purpose, the wires need to be "doped", i.e. provided with small amounts of atoms of other elements, "wrapped up" in a thin oxide and provided with metal contacts.
"But even if they do not end up in microelectronic applications, our research could show what the limits of silicon electronics really are," explains Minamisawa.
The project has been supported by the Swiss National Science Foundation and the Swiss Priority Program nano-tera.ch.
Source: http://www.rdmag.com/news/2012/10/silicon-breaking-point-could-be-basis-efficient-transistors
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Founded by Russian entrepreneur Dmitry Itskov in February 2011 with the participation of leading Russian specialists in the field of neural interfaces, robotics, artificial organs and systems.
The main goals of the 2045 Initiative: the creation and realization of a new strategy for the development of humanity which meets global civilization challenges; the creation of optimale conditions promoting the spiritual enlightenment of humanity; and the realization of a new futuristic reality based on 5 principles: high spirituality, high culture, high ethics, high science and high technologies.
The main science mega-project of the 2045 Initiative aims to create technologies enabling the transfer of a individual’s personality to a more advanced non-biological carrier, and extending life, including to the point of immortality. We devote particular attention to enabling the fullest possible dialogue between the world’s major spiritual traditions, science and society.
A large-scale transformation of humanity, comparable to some of the major spiritual and sci-tech revolutions in history, will require a new strategy. We believe this to be necessary to overcome existing crises, which threaten our planetary habitat and the continued existence of humanity as a species. With the 2045 Initiative, we hope to realize a new strategy for humanity's development, and in so doing, create a more productive, fulfilling, and satisfying future.
The "2045" team is working towards creating an international research center where leading scientists will be engaged in research and development in the fields of anthropomorphic robotics, living systems modeling and brain and consciousness modeling with the goal of transferring one’s individual consciousness to an artificial carrier and achieving cybernetic immortality.
An annual congress "The Global Future 2045" is organized by the Initiative to give platform for discussing mankind's evolutionary strategy based on technologies of cybernetic immortality as well as the possible impact of such technologies on global society, politics and economies of the future.
Future prospects of "2045" Initiative for society
2015-2020
The emergence and widespread use of affordable android "avatars" controlled by a "brain-computer" interface. Coupled with related technologies “avatars’ will give people a number of new features: ability to work in dangerous environments, perform rescue operations, travel in extreme situations etc.
Avatar components will be used in medicine for the rehabilitation of fully or partially disabled patients giving them prosthetic limbs or recover lost senses.
2020-2025
Creation of an autonomous life-support system for the human brain linked to a robot, ‘avatar’, will save people whose body is completely worn out or irreversibly damaged. Any patient with an intact brain will be able to return to a fully functioning bodily life. Such technologies will greatly enlarge the possibility of hybrid bio-electronic devices, thus creating a new IT revolution and will make all kinds of superimpositions of electronic and biological systems possible.
2030-2035
Creation of a computer model of the brain and human consciousness with the subsequent development of means to transfer individual consciousness onto an artificial carrier. This development will profoundly change the world, it will not only give everyone the possibility of cybernetic immortality but will also create a friendly artificial intelligence, expand human capabilities and provide opportunities for ordinary people to restore or modify their own brain multiple times. The final result at this stage can be a real revolution in the understanding of human nature that will completely change the human and technical prospects for humanity.
2045
This is the time when substance-independent minds will receive new bodies with capacities far exceeding those of ordinary humans. A new era for humanity will arrive! Changes will occur in all spheres of human activity – energy generation, transportation, politics, medicine, psychology, sciences, and so on.
Today it is hard to imagine a future when bodies consisting of nanorobots will become affordable and capable of taking any form. It is also hard to imagine body holograms featuring controlled matter. One thing is clear however: humanity, for the first time in its history, will make a fully managed evolutionary transition and eventually become a new species. Moreover, prerequisites for a large-scale expansion into outer space will be created as well.
Key elements of the project in the future
• International social movement
• social network immortal.me
• charitable foundation "Global Future 2045" (Foundation 2045)
• scientific research centre "Immortality"
• business incubator
• University of "Immortality"
• annual award for contribution to the realization of the project of "Immortality”.
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