Doped and deadly

Published: Wednesday 30 September 2009

-- BY ITSELF, silicon is not an effective conductor. It does not leave its electrons free for smooth flow of information. To make it less rigid, impurities are introduced into a pure silicon chip. The impurities free an electron or two and make the element a better conductor. This is called doping--a process essential to creating the heart of every electronic device.

Concentrations as small as one atom of boron, arsenic or phosphorus (impurities) per 100 million atoms of silicon have been effective so far. But with the world increasingly devising chips smaller than a strand of human hair, the definition of doping had to change, too. This was the challenge James Tour and his team of researchers from the Rice University accepted. The study published in the July issue of the Journal of the American Chemical Society suggests attaching a single layer of molecules on to the surface of the silicon chip, rather than mixing them in, serves the same purpose as doping but works better at the nanolevel. For this,

the team bathed the nanosilicon chip in the dopant solution, just like one creates a photographic film. "We call it silicon with afterburners," said Tour who teaches chemistry at Rice University.

The nanochips have very little volume and you have to deal with them accordingly," he explained. Dopants mixed with silicon in the usual way destroy its homoge - neity and hamper conductivity.

Years of research into replacing silicon with a better semiconductor has yielded little. "So we decided to complement silicon, rather than supplant it," said Tour. "This research gives the Intels and the Samsungs of the world another tool to try, and I guarantee you they'll be trying it," he added.

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.