Progress Toward Single Molecule Transistors

Fungii writes "There is an amazing story over at sciencedaily.com saying two research teams have managed to create single molecule transistors, looks like we don't have to worry about limitations on feature sizes for a while."

Comments

And You Thought...

[Myriad]

...Hand soldering SMT's was a bitch!

Re:And You Thought...

[PacoTaco]

Now someone will need to invent the "soldering ion."

The bad news:

[RyanFenton]

The molecules involved in making the transistors, metal vanadium, are individually the size of golf balls.

;^)

Ryan Fenton

Practicality?

[DoctorFrog]

...but what does it actually mean on a practical level?

This means very little on a practical level at the moment; it's more an indication of what's possible than anything we're going to see actually used in the next few years (IMHO). It's an ongoing question just how small a transistor can get and still be functional, and this seems to be an answer to that: it can get molecule-sized. Whether a molecule-sized transistor can or will be actually be usefully incorporated in any practical device is another question (well, technically it's two other questions).

At the very least a practical device using transistors that small would have to have a radically different design from present-day circuits, including vastly larger error-checking capabilities and probably some self-repairing abilities. Heat is a problem even now, and in circuits on this scale it wouldn't take much for the circuitry to literally shake itself apart. Quantum effects, which are negligible on today's scale, would introduce all kinds of errors into both the input and output of such small circuits if you tried to simply copy the same structure onto the smaller scale.

Speaking of which, the issue of actually hooking in I/O at such a scale is both a major hurdle for some applications, and a major possibility for practical use in others. For example, this is the kind of scale you'd want if you're going to try to splice more-or-less traditional electronic circuitry directly into fine nerves; when the electronic eyes currently just coming into being become fine-grained enough to support normal vision, they'd probably need extremely fine connections to individual nerve fibres in the retina.

This is a real wowser of a breakthrough, and major kudos rightfully go to both teams. It shows that there's a long way to go before transistor-type circuits can't be made smaller. By the time we actually get that far down the Rabbit Hole it's likely that we'll also have other information-processing techniques available, such as quantum computing (and this technology, once developed, might be just what is needed to usefully access the output of qubit-based systems).

Re:English, please?

[Compuser]

Current scale for transistors is about 90 nm
(current production technology is 130 nm).
Single molecule transistor scale would be 1 nm.
So oversimplifying a bit, this is 100 times
smaller than current tech.

Very high

[Futurepower(R)]

The physics is such that the theoretical frequency response must be very high. The only problem could be capacitance on the input. I wonder about the gain, also.

Re:This has already been done.

[wildsurf]

Further, Tour and his group have synthesized molecular transistors (he calls them "Moleisters") about a year and a half ago.

"Moleisters"?? What awful nomenclature, sounds scandalous. How about switching it around, call them "Transeculars." Hmm, that's not much better... But hey, it's all good, whatever helps them sustain an electron.

Re:Fabrication?

[Animats]

Right now, the mask makers are ahead of the transistor designers. I went to a talk recently where images were shown of lines fabbed using subwavelength interference masks. This wasn't extreme UV; this was stuff you could do in an existing fab. They could lay out lines and transistor geometries an order of magnitude smaller than current production. But the transistors don't work. Just scaling down existing transistor designs doesn't work electrically. That problem can probably be overcome; though. The people talking were just making better masks, leaving the device physics problem will be addressed by others. This new result indicates that we're not out of room on the device physics end.

Despite all this, everyone agrees that some time around 2015, plus or minus a few years, we hit the fundamental limit on flat silicon wafers: the atoms are too big.

There may be ways around that, but remember that the real limit is cost per gate. A technology that provides higher density at higher cost per gate isn't going anywhere. After all, even now, the physical space taken up by ICs isn't a problem.

Yup, wiring is the issue

[WillWare]

This is one of the big problems. People have been coming up with switching devices for a while now. It's been done with rotaxane , it's been done with nanotubes. As you point out, the really tricky problem is specific wiring.

Some programmable logic technologies handle wiring with a uniform sea of logic gates connected by fuses, and you create a particular logic circuit by selectively blowing fuses. The HP/UCLA rotaxane work involves essentially the same idea, using molecular switches at the intersections of a 2D grid of molecular wires. In addition to some discussion here on Slashdot, there is more at Nanodot, and a fairly extended discussion on sci.nanotech.

Solving the problem of routing specific wires to specific gates, and doing it in a way that's reliably manufacturable in mole quantities, will pretty much relegate today's foundries to niche markets. But that's probably a long way off, numerous problems to solve to get there. Interesting times ahead.