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Where Do We Stand with Molecular Electronics?

Last week I highlighted some recent research in the UK that successfully built 3D molecular structures on a surface using buckyballs and the process of self assembly. 

As exciting as this work is, I felt obliged to caution that this work is not going to usher in the era of molecular electronics anytime soon as was implied by some exuberant reports I had read on Twitter feeds.

But the prospect of building electronic devices with molecules is an appealing concept that remains the ultimate aim of many researchers investigations into nanostructured materials.

Over at Nanowerk they have a nice reexamination of molecular electronics and highlights recent work being done in Germany that has “demonstrated that rigidly wired molecules can emit light under voltage bias.”

The researchers from the Electronic and Optical Properties of Molecular Nanostructures group at Karlsruhe Institute of Technology (KIT) have reported their findings in the November 28th issue of Nature Nanotechnology.

This, of course, is not the first time that electroluminescence has been observed in molecule. However, in those previous instances it came as a result of being in contact with the tip of a scanning tunneling microscope or in nanocrystals or nanoclusters.

As Ralph Krupke, who heads the KIT research group, told Nanowerk, "In our recent work, our motivation was to form a rigid light-emitting device based on single molecules."

The design they developed with the assistance of Marcel Mayor from the University of Basel in Switzerland involved the placing of “a rod-like molecule between two metallic single-walled carbon nanotube electrodes forming a rigid solid-state device.” 

“The major challenge was to integrate a bottom-up object (molecule) into a top-down structure (electrodes) and to have control over the critical dimensions,” explained Krupke to Nanowerk. “Moreover the electronic and optical properties of the molecule and the carbon nanotube electrodes had to be tailored such that electron transport and light emission is possible."

Molecular Self Assembly on a Surface Moves from 2D to 3D

In what is being described as the first demonstration of building a 3D molecular structure on a surface, researchers at the University of Nottingham have introduced Buckyballs (C60 molecule) to a surface and found that molecules would self-assemble around the spherical shaped molecule into a 3D structure.

The research, which was initially published in the journal Nature Chemistry, took the work that has been done thus far in having molecules attract other molecules into 2D planar formations and moved it a step beyond by using a non-planar molecule like C60 to promote the growth of the host molecule into self-assembled formations that are both above and parallel to the surface, i.e. in three dimensions.

One of the authors of the research, Professor Neil Champness, had some colorful quotes to describe both the nature of self-assembly and how these 3D structures differ from their 2D precursors.

"It is the molecular equivalent of throwing a pile of bricks up into the air and then as they come down again they spontaneously build a house,’ Champness said in describing the process of self assembly.

"Until now this has only been achievable in 2-D, so to continue the analogy the molecular 'bricks' would only form a path or a patio but our breakthrough now means that we can start to build in the third dimension. It's a significant step forward to nanotechnology," Champness added.

I like to add a caveat to these stories. As innovative as this research is we shouldn’t be expecting molecular electronics in the near future.

Carbon Nanotube Production Gets a Little Greener

No sooner do the Friends of Earth highlight how the production of nanomaterials probably consumes more energy than it saves, than research at MIT has demonstrated a method for producing carbon nanotubes that reduces emissions of harmful byproducts at least ten-fold and up to a factor of 100 and cuts the amount of energy used in half.

The research, which was initially published in the American Chemical Society’s journal ACS Nano, has provided a relatively simple way of reducing the byproducts that come from the catalytic chemical vapor disposition (CCVD) method for making multi-walled nanotubes.

Multi-walled carbon nanotubes (MWNTs) have undergone a huge expansion in capacity over the last three years with one producer, Bayer Material Science, having added nearly 600% more capacity this year from its 2007 levels. Bayer was not alone. Nanocyl and Arkema have been in a capacity race along with Bayer over these last three years, matching nearly every capacity increase.

This may drop the price of MWNTs considerably (by some estimates as much as half over the last five years), but it also is not very eco-friendly. CCVD is estimated to release 97% of its initial feedstock into the air as unreacted compounds, and we’re talking real harmful stuff like benzene.

In coverage of this research over at the AIChE blog, one of the lead authors of the MIT research, Desiree Plata, explains how they replaced the process of heating carbon-based gases and instead added key reactive ingredients into the process to eliminate many of the harmful byproducts.

Now it may take some time for this get into the industrial processes of the large MWNT producers, but it could and likely eventually will. What this ultimately will result in is the production of MWNTs that is less energy intensive and better for the environment so that MWNTs can enable things like lighter wind turbines and blades and result in a net energy gain rather than loss.

If we just walk away from nanotechnology altogether, especially at this early stage, we may never get there.

Overcoming Misleading Nanotechnology Lists

There seems to be an odd fascination for some experts, journalists and other assorted types to create lists when confronted with the topic of nanotechnology.

The annually updated list that annoys me at least once a year is the Project on Emerging Nanotechnologies' Nanotech-enabled consumer product list.

As annoying as I find that list, an entirely new type of list that seems to be growing in favor is even more pointless. Their titles are usually some twist on “x number of things you should know about nanotech” or “x number of things you didn’t know about nanotech.”

My first encounter with these was in the men’s magazine Askmen.com, which got things started with “5 Things You Didn’t Know about Nanotech”. This was just the first for me in what would become a genre of nanotechnology lists that seems to me to be increasingly annoying, pointless and misleading.

Then came the far more reputable publication, at least in all things nano, Nanowerk that told us “10 things people should know”, or perhaps more appropriately 10 things you should agree with Nanowerk on when it comes to nanotech.

And now we have the publication “Discover” upping the ante by giving us "20 (that’s right twenty) Things You Didn’t Know about Nanotechnology.”

This one may be the most comical of them all, and yet still be as equally annoying as the others. What makes this list such a farce is that apparently they could only come up with 10 things so they split each one into two entries. I kid you not.

For instance the now 20-year-old event of spelling out I-B-M with xenon atoms gets two entries:

13.  In 1989, using an atomic force microscope, IBM engineer Don Eigler became the first person to move and control a single atom.

14.  Eigler and his team later used 35 xenon atoms to spell out “IBM,” thus performing the world’s smallest PR stunt.

To add insult to injury, they keep the entire misleading quality of these lists up to snuff by using artwork that depicts some “nanorobot” manipulating red blood cells.

Really, if this is the only way we have to engage people on the subject of science, and specifically nanotechnology, might we not be better off not engaging people at all?

Nano-Enabled Water Filter Brings Clean Water to Poor, Remote Regions

It seems that my criticisms of the Friends of the Earth’s (FoE) overly ideological report on nanotechnology’s role in improving our environment and enabling alternative energy are not alone. The reports continues to garner more sharp rebukes, like here  and here.

These are all well deserved criticisms in my opinion. To reinforce one of my own points that the FoE seemed to ignore, I bring you this story “Teabag filter cleans water with nanotechnology”.

Admittedly, inexpensive nano-enabled water filters are nothing new since Argonide Corporation has been around since 1994 offering more or less the same thing, but this current solution looks to be specifically targeted at providing clean drinking water to poor and remote regions of Africa.

"This project takes nanotechnology to the poorest of the poor people who live in this world, and it will make a difference in their lives," said Eugen Cloete, who in addition to inventing the filter is dean of the faculty of science at Stellenbosch University and chair of Stellenbosch University's Water Institute.

And anticipating the immediate knee-jerk reaction that this solution is probably more expensive than other methods of providing clean drinking water, Marelize Botes, who is analyzing the tea bags in her in her laboratory at the University of Stellenbosch in South Africa, said, "The filter is much cheaper than bottled water as well as any other filter on the market."

"It is simply impossible to build purification infrastructure at every polluted stream," Cloete said. "So we have to take the solution to the people. The water is cleaned right then and there when you drink from the bottle." 

Researchers from every imaginable scientific discipline looking for ways to apply nanotools and nanomaterials to every imaginable application, like clean drinking water, like clean energy, like energy conservation is not in itself a crime against the planet Earth. However, depriving the rest of us from these potential solutions may very well be.

Solution to Riddle in Fundamental Material Science Could Lead to New Age in Electronics

Researchers at Oregon State University (OSU) have reported success in creating a metal-insulator-metal (MIM) diode architecture that in the past has proven difficult to produce with high yield and top-level performance.

The research, which was initially published in the Wiley journal Advanced Materials, is being lauded as opening up a new approach to electronics.

"Researchers have been trying to do this for decades, until now without success," said Douglas Keszler, a distinguished professor of chemistry at OSU. "Diodes made previously with other approaches always had poor yield and performance.

"This is a fundamental change in the way you could produce electronic products, at high speed on a huge scale at very low cost, even less than with conventional methods," Keszler said. "It's a basic way to eliminate the current speed limitations of electrons that have to move through materials."

The OSU researchers found success in their MIM design over previous attempts through the use of an "amorphous metal contact" instead of a crystalline material.

The MIM architecture enables a quantum tunneling current flow through the insulator material, which is superior to traditional current flow that requires electrons to essentially jump across device barriers. This all translates to electronics that are faster, consume less energy and run cooler.

While this may be a diode architecture that can improve current speed of electrons that have to move through materials, it is not clear to some familiar with other MIM diode designs whether this will have much of an impact unless OSU has a working transistor (see comments).

Meanwhile the research, which was supported by National Science Foundation, the Army Research Laboratory and the Oregon Nanoscience and Microtechnologies Institute, is now seeking a patent.

NGO Challenges Use of Nanotechnology in Alternative Energy in New Report

I have long expressed my skepticism about the claims that nanotechnology would enable alternative energy solutions to compete with fossil fuels.

Now I have a companion in my challenge that I really should have expected, but still strikes me as somewhat ironic. Friends of the Earth has just released a new report (pdf) that not only argues that nanotechnology has not really delivered on its claims to be able to bring cheap solar, hydrogen and wind power to us, but also points out that the energy used in creating the nanomaterials that would enable these breakthroughs results in a net energy loss, and, of course, nanomaterials will kill us.

On balance, I have not agreed with the Friends of Earth (FoE) whether it be their tactics, their science or their politics. However, this is not to say they don’t make valid points that certainly deserve deeper investigation.

But they always end up becoming such vigorous advocates for their ultimate line of argument (big corporations and technological development is our enemy, or more accurately, the earth’s enemy) that they inevitably step over the line.

Andrew Maynard over at his 2020 Science blog takes a cursory look at the report with the tacit promise that he may come back to us with a more thorough reading of it later. But even in his quick reading of it he noticed the omission of “heterogeneous catalysts in vehicle exhausts” and “nanomaterials to develop more efficient power lines”.

From my reading of the executive summary, the FoE seems quite upset that nanomaterials are being used to improve the extraction of oil and gas. I suppose they see that as some kind of betrayal of the promise of nanotechnology, at least for use in promoting alternative energy.

The issue to me seems to be that the world is going to continue to extract oil, if nanomaterials can help in doing it more cheaply, efficiently and with the use of fewer resources, I would think that would be a good thing. But again, the FoE is so fervent in their ideologies that reducing the environmental impact of an industrial process is anathema because it perpetuates the use of the industrial process. Sigh.

I have wondered why the FoE exerts so much effort in combating the use of nanotechnologies when there are far more established and dangerous materials threatening them from afar. And I think I have an idea. Nanotechnology—or for that matter any emerging technology— that offers a solution to the world’s ills stands as an obstacle to their wish that we all live in mud huts and wear clothes from textiles we wove ourselves from sheep and cotton we raised ourselves, and on and on and on.

The irony of this is that this perspective can only come from highly affluent people who were raised and continue to live in a society built upon technological development that gives them clean drinking water, sanitary living conditions, and readily available calories for both food and energy. Meanwhile the billions who eat, sleep and live in what are virtually open sewers and who might like to have a cheap way of getting clean drinking water or someway to have electricity in their homes seem to be lost in the FoE’s self righteousness.

I welcome the FoE’s challenge to the real benefit of nanotechnology in alternative energy. However, my aim is to see that nanotechnology either actually rise up to its claims or admit that it cannot, not as the FoE seems to be doing wishing that it would all just go away.

Nanoribbons Break New Ground in Memory Storage Density

Researchers from Germany, Switzerland and Italy have demonstrated that turning graphene into nanoribbons using V2O5 nanofibers as etching masks not only dramatically improves their memory storage density over silicon-based chips but also surpasses carbon nanotubes and graphene in their transition times.

The research, which was initially published in the Wiley journalSmall, demonstrated that by depositing V2O5 nanofibers on top of graphene and then etching it with argon ion beam they were able to produce graphene nanoribbons that were less than 20 nm wide. This process also produced ribbons with smoother edges than are typically found with lithography techniques, resulting in devices made from them that have better performance characteristics.

The key to the nanoribbon’s memory storage density is that small memory cell. And according to Roman Sordan of the Politecnico di Milano, and one of the researchers on this project, that grapehene nanoribbons shrink these down to 10 nm scale.

“Indeed, the area of our new memory cell is so small that it allows for a very high storage density,” Sordan said in a story published by nanotechweb.org. “We thus expect that graphene nanoribbon memory chips will allow Moore's law to continue for the foreseeable future.”

According to Sordan in the same article, the device produced from these graphene nanoribbons has a transition time three orders of magnitude shorter than those devices made from either carbon nanotubes or graphene.

In addition, Sordan believes the versatility of these memory cells will open differenct application areas. “They can be used as both static random access memories and nonvolatile flash memories cell for ultrahigh storage density applications,” he says in the article.

Now that memory has been addressed the researchers are going to look at how their nanoribbons can be applied to digital logic gates. “We have already made graphene logic gates but think that those made from nanoribbons will be better,” says Sordan.

IBM Goes for World Record in "Noise-Free" Labs

Nearly imperceptible changes for either man or machine in temperature, movement and noise can be catastrophic for executing accurate measurements on the nanoscale.

For this reason, IBM’s new Nanotechnology Center at its Zurich, Switzerland research campus has devoted approximately 10% of the new facility’s $60 million overall cost to constructing six rooms for different microscopy tools. Not only are the labs the most isolated from noise and movement of any other similar labs in the world, but have also gone beyond the capabilities of the most sensitive detection equipment currently available to detect either movement or noise.

This week I had the opportunity to tour IBM’s still unfinished Nanotechnology Center (they expect to have the facility operational by the first half of 2011) and get a look into their new “Noise-free”  labs , in which they are planning to get their first microscopy tool by the first quarter of 2011.

When deciding to go out for a record like the most “noise-free” lab in the world, they sure didn’t make it easy for themselves with the location. While the location does keep the Nanotechnology Center on the same campus of the research facility that IBM opened back in 1956, it is less than 200 meters from a heavy rail track and it would seem by my own estimates to be a good deal closer than that to a four-lane highway.

The benchmark for the IBM scientists who designed and engineered these labs from scratch was the NIST laboratories. Now the IBM researcher who was instrumental in the design, engineering and overseeing of the construction of these facilities, Dr. Emanuel Lörtscher, and who gave the assembled European journalists a presentation on the facilities, said that the NIST facilities they were informally competing against were located in a more remote location, making IBM's achievement all the more remarkable.

In any case, what the IBM team has accomplished is significant. Every conceivable detail was addressed. For instance, rather than simply using steel-reinforced concrete a special plastic was used as the rebar. 

As mentioned, the design and engineering of this facility was done in-house at IBM Zurich, and since one of the stated goals of IBM is to deliver an additional $20 billion in revenue by 2015 and bring its earnings per share to $20 by the same year from its current level of $10 EPS, I thought I would ask as an aside whether they were considering selling this developed design and engineering skill as a service, the response I got was, “We’re considering it.”

Federal Reserve Measures Impact of Nanotechnology on Electronics

The Federal Reserve, that extra-governmental entity that has run US monetary policy for the last century, has presented some fascinating interpretations of our economic circumstances in the recent past. The most glaring examples of this has been the idea put forth from its two most recent Chairman, Ben Bernanke and Alan Greenspan before him, that there was no housing bubble. Oops.

That’s why I found the most recent announcement from one of the twelve regional Federal Reserve Banks, in this case the one in Dallas, that it was going to be hosting a one-day seminar on how nanotechnology is going to impact electronics, somewhat disturbing. "Sizing Up Nanotechnology: The Economic Impact of Nanoelectronics" as its called will assemble experts from around the country to speak on December 3 in Texas and have them address:

  • What radical innovations might remove the circuit size constraints facing today’s semiconductor industry?
  • How will nanoelectronics drive productivity, output and export growth in the U.S.?
  • What conditions are needed for the industry to maximize its potential?

I think I have an inkling of what these talking points might mean, but I have to confess phrases like “remove the circuit size constraints” have me scratching my head. And I have to ask what “industry” are they referring to when they ask what conditions are needed for it to maximize its potential.

However, I really became confused when they proffered that “Nanoelectronics has the potential to replace the semiconductor.” I guess I just don’t know what they mean by “nanoelectronics”, or for that matter “semiconductor”.

But I am sure the assembled experts will clear this up. I just trust that they can avoid the reading of the economic tea leaves that led them to believe there was no housing bubble.

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Nanoclast

IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

 
Editor
Dexter Johnson
Madrid, Spain
 
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Rachel Courtland
Associate Editor, IEEE Spectrum
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