Short Bytes: A new research has been published by a team at UC San Diego. The study is a proof-of-concept of a semiconductor-free microelectronic device which houses gold mushroom-shaped nanostructures on an array of parallel gold plates. To eject electrons from the gold surface, a low power laser and low DC voltage are used.
All of the fastest microprocessor chips out there feature millions of closely packed Silicon-based tiny transistors. But the fact that Silicon is a semiconductor material–having conductivity between metals and insulators–which puts a limit on a device’s conductivity and, eventually, on the processing power.
A band gap exists for the semiconductor materials and in order to enable the flow of electrons across the material, the electrons need an extra push–given by applying a voltage–to cross the band gap. Still, the electrons move slowly as they constantly bump into the atoms while they travel across the band gap.
Researchers at UC San Diego have tried to address this issue by ditching the semiconductor material for free electrons in space. The technology is similar to the century-old vacuum tube-based computers in which the flow of electrons occurs in free space. But it isn’t possible for microscale devices as it requires applying a high voltage (more than 100 volts), high power lasers, or high temperatures to kick the electrons from the surface of the material.
The team led by Dan Sievenpiper worked out a solution for their reincarnated tech. Their microscale device consists of a metasurface–featuring an array of gold mushroom nanostructure on parallel gold strips. This metasurface sits on top of a silicon wafer and has silicon dioxide layer in between.
By applying a low DC voltage (below 10V) and using a low-power laser, enough energy can be generated which is sufficient to kick out electrons from the gold metal. The new tech — currently a proof-of-concept — is able to deliver 1000 percent change in the conductivity.
The paper is published in Nature. The electron-emitting surface is scalable and can handle high power. Such devices can be used as transistors, photodetectors, or power amplifiers. The world’s first semiconductor-free and laser-controlled DARPA-funded project can be beneficial for electronic devices, photovoltaics, or environment applications.
The technology looks promising but the researchers aren’t aiming it as a full-fledged alternative. “This certainly won’t replace all semiconductor devices, but it may be the best approach for certain specialty applications, such as very high frequencies or high power devices,” said Sievenpiper. According to the researchers, for different microelectronic devices, different metasurfaces will have to be designed and optimized.
To more about the metasurface, you can read the research paper on Nature.
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