Molybdenite transistors: better than graphene?

Swiss physicists throw another, more energy efficient, material into the ring as a potential silicon substitute: molybdenite.

Graphene has received a lot of attention lately for its ability to conduct electricity and disperse heat , talents coveted in the world of tiny electronics. This week Swiss physicists are throwing another material into the ring for substituting, or complementing, silicon: molybdenite.

A mineral found in major deposits in Colorado, Utah and New Mexico, molybdenite (MoS2) is a layer of molybdenum sandwiched between two sheets of sulfur.

Molybdenite is currently found in steel alloys and lubricants, but the researchers are adding very small transistors, LEDs and solar cells to its potential future destinations. Publishing their work in Nature Nanotechnology, they demonstrate the mineral's use as a semiconductor. According to the study, their molybdenite device can consume 100,000 times less energy during a standby state than a more conventional silicon transistor.

Andras Kis of Laboratory of Nanoscale Electronics and Structures (LANES) in a statement:

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. But it's not currently possible to fabricate a sheet of silicon as thin as a monolayer sheet of MoS2.

Like graphene (a single sheet of carbon, 1-atom thick), molybdenite is a two-dimensional and less "bulky" than silicon. Graphene, however, does not have a band gap, which limits its use as a transistor. Band gaps help control the flow of electrons, switching the transistor on and off. With a 1.8 electron-volt (eV) gap, the researchers say molybdenite could do this easily.

But don't rule graphene out of the competition just yet. It's still super strong with amazing heat conductivity. And because graphene's transparent, the researchers suggest combining the two materials for areas such optelectronics and solar cells. That's teamwork.

Still, it's early days for bringing graphene into our electronic and computer chips. And even earlier for molybdenite research.

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Image: Rob Lavinsky, and EPFL

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