Materials breakthrough promises smaller chips

Carbon, just one atom thick, makes up the super-conductive substance known as graphene. Graphene now has new a competitor—silicene. And unlike graphene, silicene works in transistors.

silicene lead image

Buckled honeycomb lattice structure of silicone

Credit: University of Texas

If you haven't heard of graphene, or its new brother silicene, you will.

For the uninitiated, graphene is a super cost-effective, ultra-hard and light-weight conductor. It's better than copper at conducting and is in fact the world's most conductive substance. Silicene is similar in that it's also ultra-thin, but it has properties that may be more suited for use in chips.

We've been hearing about graphene for a while. However, this miracle substance has a slight, somewhat awkward problem for a superstar. Despite its second-coming-like trumpet blowing, it's not very good in transistors. The reason: it doesn't have the necessary logic operation capability.

Without getting into too much technical detail, it's not very good at switching on and off—a requirement in any semiconductor used in a computer chip. Graphene's energy state is full on or not.

Silicene's band gap

New kid on the block silicene, on the other hand, has what's called a band gap, a result of its buckled structure. Band gaps cause electrons to be in different states depending on the atoms present. That's what makes transistors do what transistors do—amplify and switch on and off.

To read more about this, check out Mark Peplow's article in the journal Nature.

A silicene transistor

This potential for transistor suitability in silicene is a big deal, and proof of concept is something that engineers have eagerly awaited—they've pretty much given up on graphene for chips.

Nanomaterials researchers at the University of Texas at Austin recently announced a silicene transistor proof of concept. Those researchers helped create the transistor.

Thin is good, and this proof of concept paves the way for more miniaturization in semiconductors.

What is silicine?

Silicene is similar to graphene in that it's only an atom thick. Scientists have been excited about the material but have found it difficult to work with. In fact, silicene was a purely theoretical material until just a couple of years ago. In the end, the scientists copied the structure of graphene to make it.

Silicene is not without its problems. Transistors created only last a short time when exposed to air. The next step is to figure how to solve this issue.

What is graphene?

Competing miracle substance graphene has been the futurists' darling for some years. It's further along than silicene.

Graphene is also a one atom-thick sheet of material. Carbon atoms, too, are arranged hexagonally.

Graphene production

Graphene production is simple and it can be created by simply peeling a layer of atoms from a block of graphite with sticky tape. Think the thinness of pencil mark on paper—it's the same idea.

This simple production means graphene is cheap.

In addition to its hardness and conductivity, graphene keeps getting more interesting. Graphene has recently been shown to drive an electrical current when exposed to photons, or light. In other words, it's photovoltaic, like a solar panel.

Magnetized graphene

New uses for graphene are continually being explored. They include deep-frying it in hot solvent to make efficient batteries. Graphene's most recently discovered property is its ability to become magnetized. Thus far, it has been considered a non-magnetic substance.

Scientists at the University of California, Riverside, say they have induced magnetism while preserving electrical properties. Magnetism has been induced before, but only by infiltrating the material with magnetic impurities, thus removing electrical properties.

The Riverside team say their method will make graphene potentially more useful in computers.

Well, silicene is now out there too, with its newly proven transistor compatibility. So now the race to miniaturization with these ultra-thin, ultra-conductive materials is really on.

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