Guided growth of nanowires leads to self-integrated nanoelectronics circuits


QDOTS imagesCAKXSY1K 8(Nanowerk News) Researchers working with tiny  components in nanoelectronics face a challenge similar to that of parents of  small children: teaching them to manage on their own. The nano-components are so  small that arranging them with external tools is impossible. The only solution  is to create conditions in which they can be “trusted” to assemble themselves.
Much effort has gone into facilitating the self-assembly of  semiconductors, the basic building blocks of electronics, but until recently,  success has been limited. Scientists had developed methods for growing  semiconductor nanowires vertically on a surface, but the resultant structures  were short and disorganized. After growing, such nanowires need to be  “harvested” and aligned horizontally; since such placement is random, scientists  need to determine their location and only then integrate them into electric  circuits.
A team led by Prof. Ernesto Joselevich of the Weizmann  Institute’s Materials and Interfaces Department has managed to overcome these  limitations. For the first time, the scientists have created self-integrating  nanowires whose position, length and direction can be fully controlled.
This is a SEM image of a logic circuit based on 14 nanowires
This  is a SEM image of a logic circuit based on 14 nanowires.
The achievement, reported today in the Proceedings of the  National Academy of Sciences (“Self-integration of nanowires into circuits via  guided growth”), was based on a method developed by Joselevich two years ago  for growing nanowires horizontally in an orderly manner. In the present study —  conducted by Joselevich with Dr. Mark Schvartzman and David Tsivion of his lab,  and Olga Raslin and Dr. Diana Mahalu of the Physics of Condensed Matter  Department — the scientists went further, creating self-integrated electronic  circuits from the nanowires.
First, the scientists prepared a surface with tiny, atom-sized  grooves and then added to the middle of the grooves catalyst particles that  served as nuclei for the growth of nanowires. This setup defined the position,  length and direction of the nanowires. They then succeeded in creating a  transistor from each nanowire on the surface, producing hundreds of such  transistors simultaneously. The nanowires were also used to create a more  complex electronic component — a functioning logic circuit called an Address  Decoder, an essential constituent of computers. These ideas and findings have  earned Joselevich a prestigious European Research Council Advanced Grant.
“Our method makes it possible, for the first time, to determine  the arrangement of the nanowires in advance to suit the desired electronic  circuit,” Joselevich explains. The ability to efficiently produce circuits from  self-integrating semiconductors opens the door to a variety of technological  applications, including the development of improved LED devices, lasers and  solar cells.
Source: Weizmann Institute of Science 

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