Boffins make silicon shine

First step toward better optical networks, light-driven processors

Scientists at the UK's University of Surrey have figured out how to make silicon generate light at room temperature.

It may not sound much - however, the discovery paves the way not only for better optical-to-electrical connections of the kind that connected computers to optical networks, but to give Moore's Law - that chips double in performance and and halve their size every 18 months - a push beyond the limits of micro-electronic circuitry.

The Surrey team, led by Professor Kevin Homewood, have created a silicon light emitting diode. While semiconductor LEDs have been around for ages, ones made out of silicon - the same material used to make microprocessors - haven't.

The team's breakthrough centres on inserting extra silicon atoms into a chip creating loop-like flaws within the silicon that makes up chip's circuitry. The process of confining the chip's electrons alters the material's properties, allowing it to emit light. The loops, called dislocations, constrict the electrons to such a degree that they emit light efficiently at room temperature.

Building light-emitting silicon that's efficient enough for optical networking devices is a long way off - intra-chip optical communications are even further away. However, it is the first step in connecting silicon chips directly to optical data links and eliminating all the kludgy optoelectronic circuitry needed to interface the two domains today.

That, said Homewood, will allow optical connections to shrink at the same pace as microprocessors, making them more efficient and more practical for small-scale networks and possibly even buses within computers themselves.

Ultimately, the technique might be used even within processors once current chip technology reaches the point where electronics no longer operate. Intel claims to have prototype chips whose gate lengths - the effective size of their component transistors - are down to the width of three atoms, promising processors capable of running at 50GHz.

Optical processing techniques could theoretically allow for even higher clock speeds in much smaller and smaller chips. ®

Related Link

The University of Surrey's work is detailed in the current issue of Nature here