Rocket fuel can significantly boost the speed of transistors, researchers have discovered.

The fuel, hydrazine, has turned out to be ideal in helping to make faster thin-film transistors, a crucial component of liquid crystal displays. What is more, it does so in a novel "wet" manufacturing process that should lend itself to cheaper mass production of the components.

Each pixel of an LCD is switched on and off by a thin-film transistor on the back of the display. These transistors are built up from fine layers of semiconductors deposited on a silicon substrate.

But if the semiconductor can be deposited as a liquid blob and smeared outwards by spinning the substrate like a high-speed record turntable, displays could plummet in price. Until now, however, transistors made this way have been too slow to drive liquid crystal displays.

In a spin

Now David Mitzi and colleagues at IBM's T J Watson Research Center in Yorktown Heights, New York, have managed to create fast thin-film transistors this way. The key was the discovery that the semiconductor tin disulphide, which is insoluble in most liquids, can be dissolved in hydrazine if sulphur is added to the mix.

By applying the solution to a silicon substrate and spinning it they were able to create a coating that left a layer of tin disulphide just five nanometres thick when heated.

When laced with electron-rich and electron-poor "dopants" to turn the semiconductor into a transistor, the device was 10 times better at carrying electric charge than previous transistors.

"It is certainly a step forward," says Mercouri Kanatzidiz, at Michigan State University. "They have demonstrated some very clever chemistry." He predicts that "wet" manufacture could become the method of choice for mass-producing thin-film transistors.

Journal reference: Nature (vol 428, p 299)

Will Knight