Tunneling to a speedy transistor.

Taking advantage of quantum effects can greatly speed up such crucial microelectronic components as transistors. For the last decade, scientists have been exploring the possibility of exploiting an electron's ability to slip through what would apparently be an impenetrable barrier--a quantum phenomenon known as tunneling. Now, researchers have developed an improved tunneling transistor, potentially opening the way for mass production of such devices using conventional manufacturing techniques.

"We have demonstrated real circuits that work and are easily fabricated," says J.A. Simmons of Sandia National Laboratories in Albuquerque, N.M. He and his coworkers describe their novel device in a report to be published in Applied Physics Letters.

Known as the "double electron layer tunneling transistor," the device consists essentially of two slabs of gallium arsenide, each 15 nanometers thick, separated by an aluminum gallium arsenide barrier 12.5 nm wide. Electrons in one gallium arsenide layer normally don't have the energy to traverse the barrier to get into the other layer. However, because the barrier is so thin, electrons, behaving more like waves than particles, can leak through. The tunneling electrons travel extremely rapidly and easily evade atomic impurities and crystal defects that slow down electric charge movement in conventional transistors.

The Sandia device has roughly 10 times the speed of the fastest transistor circuits now in use, Simmons says.