Nano-Computing Devices a Highlight of IEDM

The focus of the Emerging Technologies session at this year's International Electron Devices Meeting (IEDM) will be on nano-computing devices. This year marks the 50th anniversary of the meeting, which will be held Dec. 13-15 at the Hilton San Francisco and Towers.

The Emerging Technologies session chair, Clark Nguyen of DARPA, notes that the topic is perhaps more distant than usual but, nevertheless, highly intriguing. "With feature sizes for 'conventional' silicon transistor devices approaching dimensions in the tens of nanometers, and with some of us citing physical limits (e.g., the wave nature of carriers at this scale, power density, etc.) that might end our ability to continue scaling, we may be approaching a juncture where other methods for achieving devices capable of computing ought to be considered," he said. "The session aims to shed light on what computational methods might be possible via nanotechnologies." The following summaries were provided by conference organizers:

Charles Lieber from Harvard University's Department of Chemistry describes a potential solution to the "interconnect" and "manufacturability" issues often cited for nanotechnologies, in which selective nickel silicide processing techniques are used to enable self-aligned fabrication of nanowire transistors with high-current-density NiSi-based nanoscale interconnects. Because it presents a method for manufacturing nanowire transistors and circuits of them with truly nanoscale interconnects (not just lithography-defined metal interconnects), this work goes a long way toward bringing nanowire circuits closer to practical reality, according to Nguyen.

Carbon nanotube electronics and optoelectronics are the focus of work by researchers from IBM's T.J. Watson Research Center . They will present a paper that describes double-gating and chemical-doping strategies that convert ambipolar carbon nanotube (CNT) FETs into devices that behave more like bulk-switched FETs, with improved on/off characteristics. Other applications of CNTs are also described, including their use as location-tunable lightsources and light detectors. Nguyen noted that, in overcoming ambipolar tendencies, this work provides a solution to a major impedance against vertical scaling of Schottky barrier-CNT FETs, while also improving device performance toward eventual practical use.

A third paper by Mark Reed and colleagues from Yale University's Electrical Engineering Department provides insights into mechanisms for electronic transport through self-assembled molecular monolayers, and gives an overview of the various molecular transport junctions postulated for molecular electronic devices (Figure ).

An artist’s rendering of elastic and inelastic tunneling in a self-assembled molecular device. (Copyright © 2004 Mark Reed)

The paper by Leo Kouwenhoven from Delft University of Technology's Department of NanoScience reviews the latest experiments on double quantum dots and evaluates their use for spin-qubit circuits, which include not only the double quantum dots with controllable tunnel coupling, but also electron spin resonance loops to perform single-spin rotations and non-invasive quantum point contact detectors for readout.

Spintronics is the focus of a paper to be presented by David Awschalom of UC Santa Barbara's Department of Physics , specifically the latest on spin manipulation based on g-sensor modulation resonance, describing magnetic tunnel junctions, concepts for spin FETs, and other methods for exploiting spin currents and states for quantum information processing.

A final paper by Michael Roukes of Caltech's Applied Physics Department , describes nanoscale mechanical devices that offer the prospect of ultralow-power signal processing, computation and sensing, all at microwave frequencies, sub-nanosecond time scales and unprecedented sensitivity. Speculations on nanomechanical computing devices are also included, all in the context of the rich history of mechanically based logic. Nanomechanical circuits that operate through mechanical switching and resonances (rather than electrical) can have distinct power and frequency processing advantages over electronic counterparts, which could have great impact in the not-too-distant future.

For additional information on emerging technologies, go to www.semiconductor.net/emerging