Fantastic flash memory combines graphene and molybdenite

March 19, 2013, Ecole Polytechnique Federale de Lausanne
EPFL scientists have combined two materials with advantageous electronic properties -- graphene and molybdenite -- into a flash memory prototype that is promising in terms of performance, size, flexibility and energy consumption. Credit: EPFL

Swiss scientists have combined two materials with advantageous electronic properties—graphene and molybdenite—into a flash memory prototype that is very promising in terms of performance, size, flexibility and energy consumption.

After the chip, we now have molybdenite flash memory, a significant step forward in the use of this new material in . The news is even more impressive because scientists from EPFL's Laboratory of Nanometer Electronics and Structures (LANES) came up with a truly original idea: they combined the advantages of this with those of another amazing material – . The results of their research have recently been published in the journal ACS Nano.

Two years ago, the LANES team revealed the promising electronic properties of molybdenite (MoS2), a mineral that is very abundant in nature. Several months later, they demonstrated the possibility of building an efficient molybdenite chip. Today, they've gone further still by using it to develop a flash memory prototype – that is, a cell that can not only store data but also maintain it in the absence of electricity. This is the kind of memory used in digital devices such as cameras, phones, , printers, and USB keys.

An ideal "energy band"

"For our memory model, we combined the unique of MoS2 with graphene's amazing conductivity," explains Andras Kis, author of the study and director of LANES.

Molybdenite and graphene have many things in common. Both are expected to surpass the physical limitations of our current and electronic transistors. Their two-dimensional chemical structure – the fact that they're made up of a layer only a single atom thick – gives them huge potential for miniaturization and mechanical flexibility.

Although graphene is a better conductor, molybdenite has advantageous semi-conducting properties. MoS2 has an ideal "" in its electronic structure that graphene does not. This allows it to switch very easily from an "on" to an "off" state, and thus to use less electricity. Used together, the two materials can thus combine their unique advantages.

Like a sandwich

The transistor prototype developed by LANES was designed using "field effect" geometry, a bit like a sandwich. In the middle, instead of silicon, a thin layer of MoS2 channels electrons. Underneath, the electrodes transmitting electricity to the MoS2 layer are made out of graphene. And on top, the scientists also included an element made up of several layers of graphene; this captures electric charge and thus stores memory.

"Combining these two materials enabled us to make great progress in miniaturization, and also using these transistors we can make flexible nanoelectronic devices," explains Kis. The prototype stores a bit of memory, just a like a traditional cell. But according to the scientist, because molybdenite is thinner than silicon and thus more sensitive to charge, it offers great potential for more efficient data storage.

Explore further: First molybdenite microchip

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1.5 / 5 (4) Mar 24, 2013
Graphene is not the future of microelectronics IMO. It's much easier to keep the know-how of silicon and improve it: people right NOW are building transistors in sub 5 nm gate length in silicon. Graphene electronics is so detached from conventional solid state electronics, that it's not 10 years we can do all we can do with silicon in graphene and better.
3.5 / 5 (4) Mar 24, 2013
Silicon technology is based on doping. When you start to reduce the size then you can't dope the material anymore (and before you get that small then the doping process becomes so non-uniform that your structures may be small - but they'd not behave as uniformely/predictably as they'd need to). There are size limits to what you can do with that material.

Plus, high purity silicon is rare and expensive to make. Carbon is ubiquitous - and a lot stronger/less brittle than silicon. Try getting to single layer tech with silicon and it'll splinter all over the place, because you can't find a good substrate on which it will stay in one piece.
1.3 / 5 (3) Mar 24, 2013
..high purity silicon is rare and expensive to make..
The price of graphene is even higher. It's actually the most expensive material at the Earth by its volume cost.
Try getting to single layer tech with silicon and it'll splinter all over the place
This is irrelevant for applications in high-integration density electronics. Btw the thin silicone films are flexible.
4 / 5 (2) Mar 24, 2013
Graphene has actually gotten a lot easier to reproduce, and getting cheaper quite quickly.
4 / 5 (1) Mar 27, 2013
This is very awesome.

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