Researchers find molybdenite may be better suited for integrated logic circuits than graphene

Feb 01, 2012 by Bob Yirka report
Fabrication of MoS2 monolayer transistors. Image from Nature Nanotechnology, 6, 147-150 (2011) doi:10.1038/nnano.2010.279

(PhysOrg.com) -- Because of its physical limitations, silicon use in tiny integrated logic circuits will have to one day soon be replaced by something that can work in a smaller state. That is, if we want to see miniaturization of computer components to continue. For several years, graphene has been seen as the most likely heir to the throne because it’s only one atom thick, which seems to be the physical limit for non-quamtum based computers. The problem with graphene though, is that it’s not a semiconductor in its natural state; it has to be put through special processes to make it so. Molybdenite (MoS2), on the other hand is a true semiconductor and it, like graphene can be produced in atom thick sizes, perhaps making it the ideal material to replace silicon once it reaches its size limits. Andras Kis and his colleagues at the Swiss Federal Institute of Technology in Lausanne, seem to believe so, their research into a way to create an actual integrated logic circuit from this material has been published in Nature Nanotechnology.

Molybdenite is a mineral that is found in nature but can also be made in the lab. Like silicon it can sometimes conduct electricity and sometimes not depending on the level of voltage (the bandgap). The problem with using molybdenite to create atom thick integrated though, has been in figuring out how to connect a metal to them to convey the electricity. This is where the Swiss team has made a breakthrough, they’ve found they can attach an incredibly small bit of gold electrode to the molybdenite using hafnium oxide when it’s sitting on top of a base of silicon. The result is an integrated logic circuit that is thinner (just 0.65nm) than one that can be made from silicon. And, it’s much cheaper to produce than one of comparable size made of .

Kis and his team don’t expect the computer industry to drop silicon and take up with molybdenite any time soon though, or maybe even at all. There’s still too much to learn about the material, they write and it’s also possible that other materials such as carbon nanotubes could be a better solution in the long run. But regardless, the fact that molybdenite has been shown to be a viable alternative for silicon is likely to take a little of the pressure off of chip makers as the limits of eventually force manufactures to turn to something else.

Explore further: Thinnest feasible nano-membrane produced

More information: Single-layer MoS2 transistors, Nature Nanotechnology, 6, 147–150 (2011) doi:10.1038/nnano.2010.279

Abstract
Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS2 have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5–3 cm2 V−1 s−1 range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS2 mobility of at least 200 cm2 V−1 s−1, similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 108 and ultralow standby power dissipation. Because monolayer MoS2 has a direct bandgap16, 18, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS2 could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.

Related Stories

First molybdenite microchip

Dec 05, 2011

(PhysOrg.com) -- Molybdenite, a new and very promising material, can surpass the physical limits of silicon. EPFL scientists have proven this by making the first molybdenite microchip, with smaller and more ...

IBM creates first graphene based integrated circuit

Jun 10, 2011

(PhysOrg.com) -- Taking a giant step forward in the creation and production of graphene based integrated circuits, IBM has announced in Science, the fabrication of a graphene based integrated circuit on a s ...

IBM introduces new graphene transistor

Apr 11, 2011

(PhysOrg.com) -- In a report published in Nature, Yu-ming Lin and Phaedon Avoris, IBM researchers, have announced the development of a new graphene transistor which is smaller and faster than the one they i ...

Recommended for you

Thinnest feasible nano-membrane produced

Apr 17, 2014

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Apr 17, 2014

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

(Phys.org) —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 0

More news stories

'Exotic' material is like a switch when super thin

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

Innovative strategy to facilitate organ repair

A significant breakthrough could revolutionize surgical practice and regenerative medicine. A team led by Ludwik Leibler from the Laboratoire Matière Molle et Chimie (CNRS/ESPCI Paris Tech) and Didier Letourneur ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...