New Technique To Develop Single-Molecule Diode

William Robinson writes: Under the direction of Latha Venkataraman, associate professor of applied physics at Columbia Engineering, researchers have designed a new technique to create a single-molecule diode, that has rectification ratio as high as 250, and 'ON' current as high as 0.1 microamps. The idea of creating a single-molecule diode was suggested by Arieh Aviram and Mark Ratner who theorized in 1974, which has been the 'holy grail' of molecular electronics ever since its inception to achieve further miniaturization, because single molecule represent the limit of miniaturization.

Comments

The limit? Not really.

[ArcadeMan]

I heard about an inventor that made a machine that could shrink objects. Nearly lost his kids in his backyard, too.

No mention of frequency

[Anonymous Coward]

It would be nice to know if these things will motor fast enough to directly rectify visible-light frequencies for use in nano-antenna based solar cells

Molecules

[Anonymous Coward]

Huh? A silicon wafer is essentially a perfect crystal and therefore a single molecule. Without saying how large their molecule is this is meaningless. (I suppose I could try reading the article. Nah.) I'd say a single atom is the ultimate limit. (Without resorting to impossible physics.)

Re:Molecules

[rubycodez]

No, the term "molecule" is not used for atoms bound in crystals (either ionic or covalent), metals or glasses.

Limits?

[Millennium]

Is one molecule truly the limit? Certainly it is as long as we view the various components of electronics as discrete objects: you can split a molecule, but this results in smaller molecules (of different types, but molecules all the same), so miniaturization becomes a race to see who can make the smallest molecules act as the different kinds of components.

But the integrated circuit allowed for many components to be combined into a single discrete object. Does physics allow for the possibility of doing this on a molecular scale: a "molecular integrated circuit", where individual atoms within a molecule act as components that affect how charge flows through the molecule's chemical bonds?

Obviously, our technology is not at the point where such a thing could be created. It may very well require molecules to be assembled atom-by-atom. What I'm asking is physics as we currently understand it allows for the possibility of such a molecule.

Re:Limits?

[drinkypoo]

Obviously, our technology is not at the point where such a thing could be created. It may very well require molecules to be assembled atom-by-atom.

That doesn't actually preclude our doing it, although we won't be able to do it with a robot arm any time soon. (Would love to be wrong.) It might be possible to do it with biotech, though.

Re:Limits?

[SuricouRaven]

You could go smaller. P-orbitals are largely independant: You might be able to get one atom to be part of three diodes at once, with the individual orbitals becoming components. It'd be silly-unstable though, you'd have to keep the thing on helium cooling and try not to whisper too loudly nearby.

Re:Limits?

[Richard Kirk]

The ideal first target is probably memory. That is a circuit that is made from the same few elements banged out billions of times. If you can make a crystal out of memory elements, then you would be able to have enormous memory densities. You could have a mole of bits for a few hundred grams of material.

The barriers are enormous. We will have to re-invent every part of a circuit at smaller scales The main barrier is probably getting the money to do the research, because it will take many decades to do this before we start getting any money back, whereas if we improve the packing density of silicon circuits by (say) 10% then we get a huge savings world-wide straight away.

There are other possible products. It would be a lot easier to make a molecular equivalent of tape. The tape might be made of square molecules such as porphyrins, with some magnetic component at the centre, and reactive groups at the corners so it forms into a ribbon or tape with sprockets at the edge. This tape would assemble itself. We would then have to make a reader, but that might be possible without full molecular circuitry. This is not as neat as the solid-state molecular circuit solution, but things like this might be useful stepping stones on the way.

Only ONE Molecule?

[freeze128]

I'm going to need a smaller soldering iron.

tiny keyboard

[wasteoid]

The keyboard must be tiny!

Re:single molecule represent the limit of miniatur

[rubycodez]

gaps with certain shapes can rectify at the quantum level also, I'm calling BS on the lower size limit too

Re:The limit of miniaturization?

[rubycodez]

Indeed, gap geometries can be made that have rectifying properties at the quantum level. How small can nothing get?

a couple million microdiodes a stack

[swschrad]

and 4 or 5 rectifier stacks to power a linear amplifier for ham radio. those microdiodes better be damn cheap.

Depends on the size of the molecule.

[Wargames]

World's largest molecule: 250 million atoms / 10 nanometers:
http://www.newscientist.com/ar...

Re:The limit of miniaturization?

[gTsiros]

The atom *is* the indivisible unit of matter. You have atoms of some element... let's use Fe. Once you divide an iron atom you no longer have iron, but *subatomic particles* which no longer comprise matter, neutron stars and bose-einstein condensates notwithstanding.

Terahertz frequencies would enable nantennas

[GPS Pilot]

Nantennas can't compete with photovoltaic cells because current diodes can't operate at terahertz frequencies. http://en.wikipedia.org/wiki/N...

Hope this tiny diode can finally jumpstart the nantenna industry, and kick off an efficiency race with the PV industry. That would be fun times!

Re:The limit of miniaturization?

[cheesybagel]

By that logic molecules are indivisible as well.

Re:The limit of miniaturization?

[gTsiros]

No. Think again.

Re:The limit of miniaturization?

[q4Fry]

By that logic, so are you.