09-06-2008 23:48

Nanotech Grows Up


In: Technology Review.com

Nanotech Grows Up
By Stacy Lawrence June 2005

Nanotechnology research and development funding almost doubled to more than $10 billion in 2004 from the previous year. Most of the increase was driven by a big jump in corporate and private funding, which grew by 160 percent, while government and academic research outlays on nanotech R&D increased by a vigorous, but less outstanding, 37 percent. Japan led the way, with expenditures approaching $4 billion; the United States, however, was not far behind, with spending of about $3.4 billion.

The expected payoff for all this investment could be huge, even over the next few years. Nanotech was already a $10 billion market last year, and that is expected to triple by 2008. Much of that growth will result from new nanomaterials. By 2008, more than $100 billion in products will likely involve some type of nanotechnology.

Still, only about half of Americans have heard anything about nanotechnology. Much has been made of the potential nanotech risks, from uncontrollable nanorobots to the breathing in of nanoparticles. Not surprisingly, public fears are directly correlated with the amount of knowledge that people have about nanotech: the less knowledge, the more fear.

By Monya Baker (editor) July 2005

Plastic That Performs
Organic transistors get up to speed

Context: Organic transistors, which are made from semiconducting plastics, are cheap to manufacture. Although they enable thin, bendable electronics, so far they can't implement the fastest, most efficient circuit designs, because the plastics can't transport electrons. Instead, they rely on a flow of positive charges, or electron "holes," to pass current, which limits their use. Now, in a surprising discovery, Lay-Lay Chua at the University of Cambridge and Peter Ho at the National University of Singapore have shown that the transistors' inability to move electrons is due not to the plastic itself but to an interaction with other materials in the transistor.

Methods and Results: In a transistor, current passes through a semiconductor under the control of a gate electrode.

The gate electrode is separated from the semiconductor by an insulator, typically silicon dioxide. In conventional silicon

transistors, electrons pass through the semiconductor without interacting with the insulator. But in most plastic semiconductors, atoms at the interface between the insulator and the plastic trap electrons, so they can't flow through the transistor. By carefully designing an alternative insulator to replace silicon dioxide, Chua, Ho, and colleagues demonstrated that organic semiconductors can indeed conduct electrons. The discovery could make for simpler, higher-quality organic transistors that can implement the most commonly used designs.


































































































































































































































































































































































































































































































































































































































































































































































































































































Why It Matters: Organic transistors can be built using relatively cheap fabrication technologies such as ink-jet printing. The new insulator should let such cheap transistors perform many more tasks. The first application that beckons: electronically active tracking labels known as radio frequency identification (RFID) tags. With the new understanding of organic transistors provided by Chua and his colleagues, fast and cheap plastic electronics could soon be as ubiquitous as ink.

Source: Chua, L.-L., et al. 2005. General observation of n-type field-effect behaviour in organic semiconductors. Nature 434:194-9.




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