The Department of Cognitive and Neural Systems (CNS) and the Center of 
Excellence for Learning in Education, Science, and Technology (CELEST) 
will host two presentations on nano-computing from 10:00 to 11:30 AM on 
Thursday, Feb 28, 2008 in Room B02 of the CNS building at 677 Beacon 
Street.


Greg Snider: Implementing Laminar Neural Circuits in a Nano/CMOS Hybrid

Duncan Stewart: Electrons and Ions: The Future of Nanoscale Electronics

Snider abstract: Implementing Laminar Neural Circuits in a Nano/CMOS 
Hybrid Neuromorphic hardware has long been hindered by the difficulty of 
implementing "synapses" efficiently--they simply require too much area. 
Dynamical resistive nanodevices, each occupying an area no larger than 
30 nm X 30 nm, can (with some tricks) supply a multiplicative transfer 
function and implement correlational learning laws such as gated 
steepest descent. Using conventional CMOS for neurons, nanowires for 
axons and dendrites, and memristive nanodevices for synapses, I'll 
present an architecture for implementing fundamental cortical circuits 
and combining them into laminar, cortex-like structures. The resulting 
circuits should be about 1000 times denser than is possible with a 
conventional, CMOS-only implementation.

Snider bio:
Greg Snider is a researcher at Hewlett-Packard Laboratories, 
investigating nanoelectronic architectures, circuits, compilation and 
simulation. Previously he has worked in communications, processor 
design, medical instrumentation and imaging, networking, operating 
systems, computer security, memory systems, compilers, hardware and 
software synthesis, e-services, simulation and programmable hardware. In 
the early 1990’s, he was the architect and compiler designer of the 
Teramac simulation system, a defect-tolerant computer built from 
hundreds of custom field programmable gate arrays.

Stewart abstract: Electrons and Ions: The Future of Nanoscale 
Electronics Titanium metal is widely used as a top metal contact for 
nanoscale molecular electronic devices, where it has been assumed to 
form a few-atom-thick Ti carbide overlayer. Using a vacuum delamination 
technique we expose and analyze chemically pristine buried 
titanium/organic monolayer interfaces from devices that have displayed 
‘molecular electronic switching’. We establish that under many 
conditions the titanium instead forms a few-nanometer-thick Ti oxide 
overlayer. Both TiO2 and reduced TiOx species exist -- this mixed 
stoichiometry Ti oxide is responsible for the electronic switching.

In the field of ‘conventional’ nano-electronics, oxide based 
electrical-resistance switches are pursued for next generation 
nonvolatile random access memories (R-RAMs).  However, the 
metal/oxide/metal switching mechanism is poorly understood.  We 
demonstrate in Pt/TiOx/Pt nanocrosspoint devices that the switching is 
channeling (on) and recovering (off) the Schottky barrier at the Pt/TiO2 
interface due to the creation and drift of positively charged oxygen 
vacancies under electric field.  Engineered oxygen vacancy profiles 
predictively control the switching polarity and conductance to support a 
general physics model of switching in these devices.

Nanoscale switches that combine such ionic and electronic dynamics have 
the potential to both transform the non-volatile RAM memory market and 
provide disruptive new electronic logic functions, including 
synapse-like devices for neuromorphic computing.

Stewart bio:
Duncan Stewart is a research physicist at Hewlett-Packard Laboratories 
in the Quantum Science Research group. He received a B.A.Sc. in 
Engineering Physics from the University of Toronto in 1992 and a Ph.D. 
in Applied Physics from Stanford University in 1999, where he studied 
nanoscale electron transport. He joined HP Labs in 1999, and has since 
worked extensively on nanoscale hybrid organic/inorganic devices, with 
efforts in both basic science and applied nanotechnologies. Basic 
science efforts focus on the challenging physical and chemical 
characterization of nanoscale interfaces, particularly organic/inorganic 
structures. Nanotechnology contributions include molecular-scale 
electronic switching, demonstrations of electronically addressed 
nano-crossbar memory at world-record densities, and the first 
demonstrations of nano-crossbar logic circuits with transistor-like 
functionality. Stewart has published more than 20 reviewed scientific 
papers and authored more than 20 patents in the area of nanoscale 
electronics and materials.

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