Using silicon nanowires for  the next generation of computers requires careful consideration

Researchers at the Max Planck Institute in Halle, have been looking at the electrical properties of monocrystalline silicon nanowires implanted with foreign atoms (dopants) such as born and phosphorous. These atoms should help in increasing the electrical conductiveiy of the nanowires, but so far, no one has characterised the behaviour of these dopants in detail.

Computer chips are getting smaller and more powerful by packing more transistors into the same space. Up until now all these structures have been two dimensional. A possible route to new chip architecture is to make them three dimensional, by building tansistors which stick out of the substrate.

These transistors could be made of silicon nanowires and while fabrication of three dimensional arrays of these wires has been achieved, there is little known about how to modify the electrical properties of the wires to make them more reliable and efficient.

Using a technique known as scanning spreading resistance microscopy, SSRM, the researchers looked at nanowires with diameters of 100nm to 300nm. They found that the dopants tend to drift to the surface of the wires, which partially inactivates them.

These new results are important when considering the design of three dimensional chips and could make the difference between having chips with superior function or having a useless chip!