Graphene Gets Some Competition.


Graphene Gets Some CompetitionGraphene is about to get some competition, at least in the world of complex electronic circuits, according to MIT. According to the MIT press release:

 “Wang had been struggling to build circuits on graphene for his doctoral thesis research, but found it much easier to do with the new material. There was a “hefty bottleneck” to making progress with graphene, he explains, because that material lacks a bandgap — the key property that makes it possible to create transistors, the basic component of logic and memory circuits. While graphene needs to be modified in exacting ways in order to create a bandgap, MoS2 just naturally comes with one.

The lack of a bandgap, Wang explains, means that with a switch made of graphene, “you can turn it on, but you can’t turn it off. That means you can’t do digital logic.” So people have for years been searching for a material that shares some of graphene’s extraordinary properties, but also has this missing quality — as molybdenum disulfide does.”

I’m all in favour of anything that ushers in the next generation of new technology faster and cheaper, and if molybdenum disulphide, beats out graphene in this electronic sector, MoS2 it’s going to be. There’s plenty of other uses for graphene, with more being discovered just about every week. Unless tweaked graphene comes with major benefits over MoS2 in electronics, no one is going to build a more expensive mousetrap. But as professor Palacios says:

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" he thinks graphene and MoS2 are just the beginning of a
new realm of research on two-dimensional materials. “It’s the most
exciting time for electronics in the last 20 or 30 years,” he says.
“It’s opening up the door to a completely new domain of electronic
materials and devices.”

One-molecule-thick material has big advantages
MIT researchers produce complex electronic circuits from molybdenum disulfide, a material that could have many more applications.
David L. Chandler, MIT News Office August 23, 2012

The discovery of graphene, a material just one atom thick and possessing exceptional strength and other novel properties, started an avalanche of research around its use for everything from electronics to optics to structural materials. But new research suggests that was just the beginning: A whole family of two-dimensional materials may open up even broader possibilities for applications that could change many aspects of modern life.

The latest “new” material, molybdenum disulfide (MoS2) — which has actually been used for decades, but not in its 2-D form — was first described just a year ago by researchers in Switzerland. But in that year, researchers at MIT — who struggled for several years to build electronic circuits out of graphene with very limited results (except for radio-frequency applications) — have already succeeded in making a variety of electronic components from MoS2. They say the material could help usher in radically new products, from whole walls that glow to clothing with embedded electronics to glasses with built-in display screens.
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Integrated Circuits Based on Bilayer MoS2 Transistors

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), have been shown to exhibit excellent electrical and optical properties. The semiconducting nature of MoS2 allows it to overcome the shortcomings of zero-bandgap graphene, while still sharing many of graphene’s advantages for electronic and optoelectronic applications. Discrete electronic and optoelectronic components, such as field-effect transistors, sensors, and photodetectors made from few-layer MoS2 show promising performance as potential substitute of Si in conventional electronics and of organic and amorphous Si semiconductors in ubiquitous systems and display applications. An important next step is the fabrication of fully integrated multistage circuits and logic building blocks on MoS2 to demonstrate its capability for complex digital logic and high-frequency ac applications. This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic technology. The circuits comprise between 2 to 12 transistors seamlessly integrated side-by-side on a single sheet of bilayer MoS2. Both enhancement-mode and depletion-mode transistors were fabricated thanks to the use of gate metals with different work functions.

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