Birck Nanotechnology Center

Re-thinking electronics - from the bottom up

July 22, 2009

More than 70 graduate students from across the country and Purdue University are on campus this week to learn about a new approach to 21st century electronic materials and devices.

A team of Purdue faculty and students is developing this new approach to provide a conceptual and computational framework for applications of nanoelectronics to tackle challenges in information processing and storage, energy, the environment and in technologies for health care.

 

"Electronics from the Bottom Up" summer schools are conducted annually and then freely distributed through nanoHUB.org, a resource for the nanoscience and technology communities that serves nearly 100,000 users per year, half of them outside of the United States. Through a new collaboration with World Scientific, an international science publisher, low-cost lecture notes for these courses will be made available to students to complement lectures on the nanoHUB.

"More than 50 years ago, the inventors of the transistor and their colleagues at Bell Laboratories defined the intellectual foundation for the field of semiconductor electronics," said Mark Lundstrom, Purdue's Scifres Distinguished Professor of Electrical and Computer Engineering. "That framework has served the field well, leading to products from shirt pocket radios to supercomputers and cell phones. Today, it is widely felt that the future of electronics lies in nanotechnology."

When exploring new ideas for nanotechnologies, however, the traditional framework that has served researchers is frequently not the best way to think about these new problems, he said.

"What we need is to complement the traditional approach with the new insights and understanding emerging from research in nanoscience," Lundstrom said. "In the process we are led to a new, comprehensive framework that can guide the evolution of electronic devices and materials in the 21st century."

The new approach can be traced to pioneering research more than a decade ago on molecular electronics by a team at Purdue led by Supriyo Datta, the Thomas Duncan Distinguished Professor of Electrical and Computer Engineering.

"To understand the experiments that were being done, we had to take a whole new approach to electronics," says Datta. "Surprisingly, this new approach is simpler than the traditional approach and often makes cutting edge research easier to understand."

Datta teaches this material, which is usually considered appropriate for advanced graduate students, to undergraduate students at Purdue in what has become a popular course in the of Electrical and Computer Engineering. Courses are taught at Purdue, and materials, including videos of lectures, are provided on the nanoHUB.

The short courses being taught this week have attracted top graduate students from around the nation.

This summer’s graduate course focuses on treating randomness and reliability in electronics.

"In microelectronics today, the period at the end of this sentence would contain hundreds of thousands of transistors," said Ashraf Alam, a professor of electrical and computer engineering. And at this size, even a small variation in the properties of transistors can lead to dramatic variations in performance. In this summer school, we are teaching students how to think about the variability and randomness in a fundamentally new way. With the right set of tools, randomness need not be unpredictable."

Electronics from the Bottom Up is the most popular content on the nanoHUB, Lundstrom said.

"We think we have the right approach to this new field of nanoelectronics -- one that will serve as a foundation for many years," he said.

Purdue is collaborating with science publisher World Scientific to provide lecture notes and, eventually, textbooks based on the new approach. The World Scientific collaboration could speed the widespread adoption of the method, Lundstrom said.

The collaboration may lead to full-length books, also to be published by World Scientific, that will serve as textbooks and references for electronic devices and materials. World Scientific and the Purdue team will produce four volumes of material over three years. Low-cost lecture notes are expected to be priced in the $25 range.

The nanoHUB is operated by the Network for Computational Nanotechnology, or NCN, a six-university network funded by the National Science Foundation and based at Purdue. The Intel Foundation also provides support.

Today, researchers exploring nanoelectronics often apply techniques for microelectronics that they learned while students. Microelectronic device dimensions are measured in microns and nanoelectronic devices in nanometers -- a millionth or billionth of a meter, respectively.

Electronics from the Bottom Up begins by understanding the smallest structures and then builds that understanding up to the micro and even macro scales. One example is using nanotechnology to measure the electrical properties of single molecule devices. Although ordinarily a daunting task even for the most skilled researchers, seniors in Datta's course calculate the properties of molecular electronic devices within the first few weeks.

"A single molecule is a rather simple thing compared to a big chunk of silicon," Lundstrom said. " But if you try to apply concepts developed for silicon microelectronic devices to single molecule devices, they can look very complicated. If you approach the problem from the bottom up, it not only looks much simpler, it also provides a clearer description of what is happening."

The new approach is made possible by the capability -- developed about a decade ago -- of studying the electrical properties of molecule-size structures. Metal contacts are placed at either end of a molecule and voltage is applied, yielding information about its electrical characteristics.

Datta reasoned that this newly developed capability of measuring the electronic properties of single molecules could lead to a more general approach to understanding electronic conduction in small devices. "Too much time is spent teaching students about concepts and issues specific to large conductors that cannot even be applied to small conductors," Datta said. "In order to teach students, especially undergraduates, I developed a very different approach that allowed people to get into cutting-edge research, almost from day one."

The initial materials in the educational initiative are being developed by Datta, Lundstrom and Alam.

World Scientific, headquartered in Singapore, publishes more than 400 books and about 80 journals a year in the fields of science, technology, medicine, and business and management.

 

Writer: Emil Venere, 765-494-4709, venere@purdue.edu

 

Sources: Mark Lundstrom, 765-494-3515,lundstro@purdue.edu

Supriyo Datta, 765-494-2706, datta@ecn.purdue.edu

Ashraf Alam, 765-494-6441, alam@purdue.edu

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