Researchers from the Swiss Federal Institute of Technology have created integrated circuits using single-atom-thick molybdenite, a substance that’s very similar to graphene. Molybdenite logic has very similar characteristics to its silicon-based cousins, but because single sheets of the material are just 0.65nm thick it can be used to make very small, very power-efficient transistors.
Molybdenite (pronounced mol-IB-dee-nite) is a mineral of molybdenum sulfide, and looks and feels a lot like graphite. Like graphite, it has a layered crystalline form that makes it a good lubricant, and a good target for producing single-atom-thick layers. Just after graphene was famously synthesized from graphite using sticky tape, molybdenite flakes were also created using the same technique. For some reason no one has coined the term “molybdenene” — maybe I can be the first. Though, looking at it written down like that, maybe there’s a reason we don’t call it molybdenenenene…
As you know, graphene is undeniably one of the most miraculous materials ever discovered — it’s probably the answer to our battery dependency woes, amongst other things — but it lacks one very important feature that semiconductors need: a reliable bandgap. Semiconductors, by definition, sometimes insulate and sometimes conduct, depending on how much voltage you run through them. The voltage difference required to switch between insulating and conducting states is called the bandgap — and graphene doesn’t have one. Molybdenite, on the other hand, has a bandgap right in the sweet spot for everyday computer chips.
To turn it into a transistor, the Swiss researcherslaid atom-thick sheets of molybdenite onto a silicon wafer, and then attached each minuscule bit to a gold electrode using hafnium oxide (a high-k dielectric used in contemporary silicon chips). In the image at the top of the story, each of the thin tips is a tunnel field-effect transistor (pictured right).
In essence, this means that molybdenite offers a viable alternative once we reach the physical limits of silicon. As we’ve mentioned many times before, though, silicon, as the reigning incumbent, will not be unseated easily. By the time Intel & Co. are forced to look beyond silicon, which is still a few years off, graphene and carbon nanotubes — both of which are capable of operating at higher speeds and lower voltages than molybdenite — might’ve reached the necessary level of maturity. Still, it’s comforting to know that, as of today, we basically have the technology to incorporate 1nm transistors into computer chips.