Graphene or Molybdenite? Which Replaces Silicon in the Transistor of the Future?

The abundant mineral molybdenite has a big advantage over graphene: a band gap

2 min read
Graphene or Molybdenite? Which Replaces Silicon in the Transistor of the Future?

Graphene is winning fans, awards and application possibilities seemingly daily. But the elephant in the room, if you will, when discussing graphene, is the problem of it lacking a band gap.

Huge strides have been made in overcoming that shortcoming, but let’s just say that not having a band gap in its nature is more than a small liability for graphene in electronic applications.

Into this mix, researchers at Ecole Polytechnique Federale de Lausanne’s (EPFL) Laboratory of Nanoscale Electronics and Structures (LANES) had their research published this week in the journal Nature Nanotechnology that offers the humble and abundant mineral molybdenite (MoS2) as an attractive alternative to silicon as a two-dimensional material (like graphene is) for replacing the three-dimensional silicon in transistors.

"It's a two-dimensional material, very thin and easy to use in nanotechnology. It has real potential in the fabrication of very small transistors, light-emitting diodes (LEDs) and solar cells," says EPFL Professor Andras Kis in an article that reports on the research.

The big advantage it has over graphene in the search for a replacement to silicon: it has a band gap. And when it comes to being better than silicon, the advantages are impressive.

"In a 0.65-nanometer-thick sheet of MoS2, the electrons can move around as easily as in a 2-nanometer-thick sheet of silicon," explains Kis. "But it's not currently possible to fabricate a sheet of silicon as thin as a monolayer sheet of MoS2."

The researchers also report that transistors made from molybdenite will use 100,000 times less energy in a standby state than traditional silicon transistors.

As explained in the Nature abstract, molybdenite does not have to stand in competition with graphene, but could complement graphene “in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.”

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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