Though superseded for most applications by the solid-state transistor, the venerable vacuum tube boasts one big advantage over its younger usurper: power. Free of stuff between its electrodes, a vacuum tube can operate at currents that would ohmically toast a transistor’s semiconducting innards. Vacuum tubes remain the technology of choice for high-power amplifiers, magnetrons, and klystrons.
Now, a team led by Wei Zhu of Agere Systems in Murray Hill, New Jersey, has built a device that could propel the vacuum tube out of its traditional niches. 1 The Agere device, a 100-μm-scale triode, exploits two of the hottest technologies of the past decade: carbon nanotubes and micro electromechanical systems (MEMS). And because the new triode sits on a silicon substrate, it could readily plug into an integrated circuit. Agere developed the triode as a proof of concept. Devices like it could end up in compact wireless transmitters.
All vacuum tubes,...
