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Nanoelectronics Come in Tiny Packages

By Andy Maslowski

Sometimes smaller is better. At least this is true in the world of nanoelectronics. But in this case we're talking about extremely small components, things a million times smaller than a grain of sand.

"Nano" is a prefix which means one billionth. When used in the field of electronics, it normally refers to items a nanometer in size, or one-billionth of a meter. Scientific breakthroughs have been made on this molecular scale, and many more are anticipâted in upcoming years. For once we are able to manipulate the configuration of objects as small as molecules, very large applications are expected in microelectronics, nanocomputers, biochemistry, physics and other disciplines.

Ongoing Research
Why do we need working devices the size of a speck of pollen or dust? Basically, it involves saving space and saving costs, improving health and our environment, and marching onward towards a future of new scientific exploration. Nanocomputer components could greatly increase computer speed and density. Micromachines could possibly travel through a person's circulatory system, fight cancer cells, clean toxins from air or water, or result in new manufacturing processes and inventions.

That is what a consortium of government agencies, private and public companies, national laboratories and educational institutions is planning. And the pursuit of finding microscopic working components is not just theoretical. A number of innovations have been made during the past few years.

In October 2014, Lucent Beli Labs, in Murray Hill, NJ, announced it had created organic transistors with a single molecule channel length, setting the stage for a new class of high-speed, inexpensive carbon based electronics. The tiny transistors are so small, one nanometer in length, that approximately ten million of them would fit on the head of a pin. Made of an unconventional organic semiconductor material called thiols and using a novel fabrication technique, they may lead to smaller, faster and cheaper computer chips in the future. Besides carbon, the thiols also contain hydrogen and sulfur.

Lucent Technologies reported scientists have been looking for alternatives to conventional silicon electronics for many years because they anticipate that the continuing miniaturization of silicon-based integrated circuits will subside in the next decade as fundamental physical limits are reached. The nanotransistors consist of a voltage converter, a standard electronic circuit module, commonly used in computer chips, that convert "0" to a "1," or vice versa.

"When we tested them, they behaved extremely well as both amplifiers and switches," explained Hendrik Schon, an experimental physicist who was the lead researcher on the nanotransistor team. "Our experiment shows it is possible to realize transistor action in a single molecule without sophisticated fabrication procedures."

It is virtually impossible to attach electrodes to a microscopically small molecule. But the Bell Labs team did this by letting the molecule find these contacts and attach itself to them, in a self-assembly process. By carefully adjusting the ratio of the thiol to the inert molecules, the scientists were able to statistically ensure that just one active molecule was present in the area on top of each electrode.

Bell Labs has a long and illustrious connection with transistors. A Bell Labs team invented the transistor in 1947, earning a Nobel Prize for Physics in 1956 and spawning the digital age. Over the years Bell Labs scientists have made other contributions to make transistors smaller, faster and more powerful.

"This work pushes the miniaturization of electronics to its final frontier," said Federico Capasso, physics research vice president at Bell Labs. "It may become the cornerstone of a new nanoelectronics era. These molecular-scale transistors may serve as the historical bookend to the transistor legacy started at Bell Labs in 1947."

Money Flow
Research and development, and the mother of R&D, funding, are growing as new technologies emerge. The U.S. federal government is spearheading this effort, to the tune of some $500 million for fiscal year 2014 through the National Nanotechnology Initiative (NNT). At least six NanoScale Science and Engineering Centers have been formed, specializing in such disciplines as information technologies, device applications, electron transport, biological and environmental engineering, and nanopatterning and detection.

Several federal agencies are involved, led by the National Science and Technology. Council. This includes the National Science Foundation, the National Institutes of Health, the National Aeronautics and Space Administration (NASA), as well as the Departments of Commerce, Defense, Energy and Transportation.

The White House is also adding support. "The president is making the NNI a top priority," explained Neal Lane, assistant to the president for science and technology. "Nanotechnology thrives from modern advances in chemistry, physics, biology, engineering, medical, and materials research and contributes to cross-disciplinary training of the 21st century science and technology workforce. The administration believes that nanotechnology will have a profound impact on our economy and society in the early 21st century."

A NNI report, published in 2014, listed more than a dozen applications showing promise. Some of the long-term possibilities included the following:
• Shrinking the entire contents of the Library of Congress in a device the size of a sugar cube through the expansion of mass storage electronics, increasing the memory storage per unit a thousand fold
• Making materials from atoms and molecules. Bottom-up manufacturing should require less material and pollute less
• Developing materials that are ten times stronger than steel, but a fraction of the weight;
• Improving the computer speed and efficiency of minuscule transistors and memory chips by several million factors
• Using gene and drug delivery to detect cancerous cells or biological agents such as anthrax
• Removing the finest contaminants from water and air and to promote a cleaner environment and larger supplies of potable water
• Doubling the energyefficiency of solar cells

Two others were nanoelectronics devices. The Vertical Cavity Selective Emitter Laser (VCSEL) relies on Superlattices with nanometer thick films is being tested for fiber optic data communications, optical sensors, encoders and extended range sensors. The High Electron Mobility Transistor (HEMT) is being tested as a major building block for sophisticated microwave and millimeter wave integrated circuits.

"These examples give an indication of the potential for nanoelectronics to completely change electronic devices in the next 10-20 years," the report stated. "Currently other new concepts such as single electronic devices, and use of molecular and quantum devices are also under investigation."

Research & Development
Government, industry and academic partnerships are working on various nanotechnologies, producing not only the requisite government reports, but evaluating different aspects of the microdomain. Dozens of companies and universities are involved.

Overseeing a number of projects is the Sandia National Laboratories in Albuquerque, New Mexico. According to information provided by Lupe Raines, Sandia scientists are concentrating on micromachines, or what it calls MicroElectroMechanical Systems, or MEMS.

"MEMS is the next logical step in the silicon revolution," a Sandia report stated. "The silicon revolution began over three decades ago, with the introduction of the first integrated circuit, which has changed virtually every aspect of our lives. The hallmark of the integrated circuit industry has been the exponential increase in the number of transistors incorporated onto a single piece of silicon.

"This rapid advance in the number of transistors per chip has led to increasing capability and performance. As time has progressed, large, expensive, complex Systems have been replaced by small, high performance, inexpensive integrated circuits. While growth in the functionality of microelectronic circuits has been truly phenomenal, for the most part this growth has been limited to the processing power of the chip.

"We believe that the hallmark of the next 30 years of the silicon revolution will be the incorporation of new types of functionality onto the chip – structures that will enable the chip to not only think, but to Sense, act and communicate as well. This revolution will be enabled by MEMS.

MEMS is a relatively new technology which exploits the existing microelectronics infrastructure to create complex machines with micron sizes, Sandia said. These machines can have many functions, including sensing, communication and actuation. Extensive applications for these devices exist in both commercial and defense systems. One estimate puts the potential market for intelligent micromachine based systems at $100 billion a year.

Sandia has developed unique technologies which enable the realization of complex mechanical systems on a chip, and the integration of these mechanical systems with on-chip control and communication electronics. One project, in cooperation with Aerospace Corporation and the Defense Advanced Research Projects Agency (DARPA), envisions the creation of nanosatellites that can operate in cooperative clusters for communications, remote sensing and action. The team tested such a PICOSAT platform in the winter of 2004. Launched on an Air Force Stanford OPAL satellite, a pair of PICOSATs, each weighing about 275 grams and about 1 x 3 x 4-inches in size, were released from the satellite under tethered guidance.

An array of MEMS RF switches on the platforms allowed accurate tracking and data downlinking from the Space Command Cheyenne Mountain Operations Center in Colorado.

"Everyday we're finding more applications for micromachine technology," the Sandia report concluded. "Our program focuses on a variety of defense and commercial applications, but we are pursuing projects ranging from inertial sensors for large-scale commercial applications to locking mechanisms for weapons systems. Since we believe that joining our resources with collaborators will further fuel the upcoming silicon revolution, we are actively seeking partners in this exciting venture."

More information about MEMS can be found at the Website: www.mems.sandia.gov. The site includes information and images of micromachines, including short moving images of working micromachines.

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