The transistor of the future may not rely on decreased size, but on a radical change in operation. The device: a quantum mechanical transistor created at Sandia National Laboratories. The transistor corresponds to turning on a light bulb--without closing a switch. With the device, electrons "tunnel" from path to path through a barrier that, according to classical physics, is impenetrable. The process resembles the way cars use a tunnel to reach a location, without having to drive over an impossibly high summit. "We have demonstrated real circuits that work and are easily fabricated," reports Jerry Simmons, leader of the Sandia development team. In the device, two gallium arsenide layers, each only 150 angstroms thick, are separated by a 125-angstrom, aluminum-gallium arsenide barrier. The tiny thickness of the barrier causes the electrons to behave like waves, which can poke into the barrier. The device may run at a trillion operations a second, roughly 10 times the speed of the fastest transistor circuits currently in use. Actual speed has not yet been measured, says Simmons, because it is "not easy to measure such high speeds, which are near the limits of measurements with conventional equipment." E-mail jsimmon@sandia..
Linear guides are one of the most important components required for the development of automated or computer-controlled equipment. Aluminum profile extrusions, used for these guides in machine design, can enable designed-in functional features.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.