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Author Interview: Nano-Semiconductors: Devices and Technology

by Editor1 last modified March 28, 2012 - 11:03

NanoScienceWorks.org looks at the dynamic area of nano-semoconductors, and how these tiny devices are fundamentally changing the worlds of computing and communications. We speak with the author of Nano-Semiconductor: Devices and Technology, Dr. Krzysztof Iniewski, who manages R&D developments at Redlen Technologies, Inc., a start-up firm in British Columbia, Canada. His research interests are in VLSI circuits for medical and security applications.

Author Interview: Nano-Semiconductors: Devices and Technology

Dr. Iniewski also serves as Executive Director at CMOS Emerging Technologies, Inc.; and a Professor at University of Alberta Electrical and Computer Engineering and Adjunct Professor at University of British Columbia.From 2004 to 2006 he was an Associate Professor at the Electrical Engineering and Computer Engineering Department of University of Alberta where he conducted research on low power wireless circuits and systems. During his tenure in Edmonton he put together a book for CRC Press “Wireless Technologies: Circuits, Systems and Devices.”

For this book, Dr. Iniwski collaborated with more than two dozen experts across many fields impacting on the present and the future of semiconductors, including CMOS, carbon nanotubes, graphene, spintronics, quantum dots, and even III-V materials.

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A Sample Chapter from Nano-Semiconductors: Devices and Technology is available at the bottom of this page.

NanoScienceWorks.org members: Purchase this book with your member discount.
For more information, see the bottom of this page.

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NanoScienceWorks.org: Your book Nano-Semiconductor: Devices and Technology delivers a whole compendium of how the design, fabrication and commercial use of nanosemiconductors will change our everyday lives in the 21rst Century (CPU, DRAM, solar, etc.).

Many of your examples seem aimed at extending Moore’s Law which states the number of transistors that can be placed on an integrated circuit doubles every 18 months-two years. What are some of the trends you see that are most exciting to you? And what are the implications of nanoscale semiconductor materials on Moore’s Law

Dr. Iniewski: Moore’s Law, if we can call it a law since it is really just a trend, has been driving semiconductor industry for the last 50 years.

For several years it has been predicted that physical barriers will limit its applicability but each time the end was announced people found ways of moving forward and making transistors smaller. Eventually scaling down will not be possible; transistors are likely not to become smaller than few atoms, unless some really futuristic concepts of quantum physics are successfully used in practice.

One major consequence of continuing Moore’s Law is enormous complexity of today’s and tomorrow’s technologies. They are becoming more expensive and fewer companies, or even countries, can afford to deploy them. For example, a cost of modern silicon fabrication facility can be as large as $5 billions and cost of designing a novel microprocessor as large as $100 millions. Under those financial conditions Moore’s law might simply end due to economical constraints.

NanoScienceWorks.org: You open your book defining nanoelectronics as an “emerging trillion-dollar industry,” and add that nanosemiconductors are an essential part of that of that vision. What types of scientific research will be most valuable in this transition to a nanoscale electronics?

Dr. Iniewski: Traditional silicon electronics is hitting performance and cost walls. Microprocessors are not getting any faster although their performance still increases due to usage of multi-cores. Memories are getting to be increasingly difficult to make to follow Moore’s law. State-of-the-art ASIC development costs are getting to hundreds of millions of dollars levels.

Moore’s law will eventually stop but improvements in lowering in energy dissipation might continue beyond physical scaling. This trend in energy efficiency that has opened the door to the increasing spread of mobile computing is being called Koomey’s Law. It states that the amount of power needed to perform a computing task will fall by half every one and a half years. Like Moore’s Law, the significance of Koomey’s Law is more as an influential observation than a scientific discovery. Both are concepts that measure what has happened and what is possible with investment and effort. Finding technologies and device nano-structures to continue following Moore’s and Koomey’s laws will be a key challenge for emerging nanoscale electronics.

NanoScienceWorks.org Let talk about how your book focuses on three (3) main area – Semiconductor Materials; Silicon Devices and Technology; and Compound Semiconductor Devices and Technology How did you choose them, and how did you go about amassing the expertise to edit a book on the subject?

Dr. Iniewski: The book is divided into three parts.

The first part deals with semiconductor materials. It covers carbon nanotubes, memristors, and spin organic devices. The second part of the book deals with silicon devices and technology. It covers BiCMOS, SOI, various 3D integration and RAM technologies, and solar cells. The third part of the book deals with compound semiconductor devices and technology.

You can think about this organization as a pyramid. Semiconductor materials form a base on which all devices are being build. Silicon devices are middle layer, a mainstream of today’s semiconductor technology. Compound semiconductors form a tip of this pyramid representing some unique applications where silicon deficiencies are supplemented by III-V materials.

NanoScienceWoirks.org: Your book also notes that many “theoretical predictions” about the use of carbon nanotubes (CNTs) for semiconductors are now confirmed in the real-world as we’re seeing the first wave CNT-based electronic devices -- for nanopackaging, for digital integrated circuits, and CNT-CMOS integrations.

In your opinion, how noteworthy and exciting are these developments? What do you see as the next steps to commercialization (of techniques or materials)?

Dr. Iniewski: Carbon nanotubes (CNTs) and grapheme based devices have very unique physical properties. Because of their outstanding electrical, thermal and mechanical properties, CNTs have been proposed as emerging materials able to give solutions to many of the problems given by the tight requirements of the technologies nodes in a nanoscale range. CNTs are considered for a large variety of micro and nano-electronics applications, like nano-wires, nano-packages, nano-transistors, and nano-antennas. While research in this field is very exciting with new papers published almost on a daily basis there is still no viable, high volume commercial application developed. In general, people underestimate how long it takes for discovery in material science to be translated in commercial reality at the device or system level.

NanoScienceWorks.org: Your book also reviews non-CNT materials for nano-semiconductors, such as memristors, and ‘spin’ devices. Can you describe these, and the properties they bring that will help promote nanoelectronics.

Dr. Iniewski: Memristors offer an amazing story in science and technology development.

In 1971, using the arguments of symmetry, Leon Chua proposed the existence of a new basic fourth circuit element that he termed the ‘memristor’. Dr. Chua deduced the existence of memristors by examining the mathematical relationships of the four basic electrical quantities (current, voltage, charge, and magnetic flux). However, it has taken almost 30 years until someone built such a devices convincing many skeptics that memristors are for real.

In the early 2000’s, researchers at HP, who were working on molecular electronics, began to see strange anomalous I-V characteristic behavior in their devices, but recognized it as being memristive. In 2008, Strukov et al. experimentally demonstrated the natural existence of memristance in nanoscale systems where electronic and ionic transports are coupled under an external bias voltage. While the future of memristors is still uncertain it is very likely that memristors will find unique application in memory or sensing applications.

Spintronics is another emerging part of nanoelectronics. In traditional electronics processing and storing of binary data is typically implemented by manipulating the charge of electrical carriers in semiconductors. Realization of the classical binary logic bits (“zero” and “one”) requires two different states. For example, in a computer memory such states are realized by different amounts of charge stored on a capacitor (DRAM concept) or by two distinct voltage levels at some circuit node (SRAM concept). An emerging technology called spintronics, on the other hand, aims to harness the spin of electrical carriers and used that spin information for information processing. This technology has already revolutionized the storage density of hard drives and might be potentially used for very low-power computation enabling us to continue Koomey’s law I talked about earlier.

NanoScienceWorks.org Tell us about your involvement as Director with CMOS Emerging Technologies and their events?

Dr. Iniewski: I started organizing CMOS Emerging Technologies event as a very small meeting of forward looking researchers back in 2005. We decided to meet the next summer in Banff and discuss in a very open fashion some emerging opportunities going forward.

The format of the talks was different than a traditional conference, it resembled in-depth tutorials describing state-of-the-art technology and future research directions, rather than presenting specific research results or commercial products. We had Jan Rabaey from Berkeley talking about short reach wireless, which 5 years later was commercialized in the form of pico-cells. Domine Leenaerts from Philips Research talked about Ultra Wide (UWB) technology that is currently used in many wireless products. Tadahiro Kuroda from Keio University presented exciting 3-D integration concept that semiconductor industry is only now trying to implement. And the list goes on (you can download all presentations from www.cmoset.com).

Although the first workshop had only 23 participants the buzz it created spread like a fire. Without any advertising the event participation started to grow almost as quickly as Moore’s law predicts, doubling number of participants in less than two years. When the attendance reached a level of 300 people we decided to limit the number of participants in order not to become yet another traditional large research conference. To maintain very high quality the meeting has become invitation only.

Our objective is to provide companies and academic institutions with a platform for showcasing their technology, innovations, products and services, and to create a stimulating common ground for exploring collaborations and encouraging discussions on emerging technologies. 2012 meeting will be held in 2012 in Vancouver with program already posted on-line, and 2013 event is scheduled to be in Whistler while 2014 in Zurich or Delft.