A team of UCLA and California Institute of Technology
chemists has created an ultra-dense memory device that stores information using
reconfigurable molecular switches. The 20 kilobyte memory device has a bit
density of 100 gigabit per square centimeter and has enough capacity to store the Declaration of Independence with
space left over. The accomplishment represents an important step toward the
creation of molecular computers that are much smaller and could be more
powerful than today's silicon-based computers.
“Using molecular components for memory or computation or to
replace other electronic components holds tremendous promise,” said J. Fraser
Stoddart, who is the Fred Kavli Chair in Nanosystems Science at UCLA and
director of the California NanoSystems Institute. “This research is one of the
only examples of building large molecular memory in a chip at an extremely high
density, testing it, and working in an architecture that is practical, where it
is obvious how information can be written and read.”
The memory is based on a series of perpendicular, crossing
nanowires, similar to a tic-tac-toe board: 400 silicon wires crossed by 400
titanium wires, each 16 nanometers wide. Sitting at each crossing of the
tic-tac-toe structure and serving as the storage element are approximately 300
bistable rotaxane molecules. These molecules may be switched between two
different states, and each junction of a crossbar can be addressed individually
by controlling the voltages applied to the appropriate top and bottom crossing
wires, forming a bit at each nanowire crossing.
Hewlett-Packard researchers just last week announced a breakthrough in using nanowires in transistor assembly as well.
“For this commercial dream to be realized, many fundamental
challenges of nano-fabrication must be solved first,” Stoddart said with regard to Caltech's breakthrough. “The use
of bistable molecules as the unit of information storage promises scalability
to this density and beyond. However, there remain many questions as to how
these memory devices will work over a prolonged period of time. This research
is an initial step toward answering some of those questions.”
“We have shown that if a wire is broken or misaligned, the
unaffected bits still function effectively; thus, this architecture is a great
example of 'defect tolerance,' which is a fundamental issue in both nanoscience
and in solving problems of the semiconductor industry,” Stoddart explained. “This
research is the culmination of a long-standing dream that these bistable
rotaxane molecules could be used for information storage.”
“It's the sort of device that Intel would contemplate making
in the year 2020,” says James Heath, who is the Gilloon Professor at Caltech. “But
at the moment it furthers our goal of learning how to manufacture functional
electronic circuitry at molecular dimensions.”
The 2020 date assumes the validity of Moore's Law, which
states that the complexity of an integrated circuit will typically double every
year, leading to a projection that the electronics industry will achieve a
device density comparable to the memory circuit in about 13 years.
However, the Caltech-UCLA team points out in their report
that manufacturers can see no clear way at present of extending this
miniaturization beyond the year 2013. The new approach of the Heath team,
therefore, will show the potential for making integrated circuits at smaller
and smaller dimensions.
“Our goal was not to demonstrate a robust technology; the
memory circuit we have reported on is hardly that,” said Heath. “Instead, our
goal was to demonstrate that large-scale, working electronic circuits could be
constructed at a density that is well-beyond 10-15 years where many of the most
optimistic projections say is possible.”
“Molecular switches will lead to other new technologies
beyond molecular electronic computers,” Stoddart said. “It is too soon to say
precisely which ones will be the first to benefit, but they could include areas
such as health care, alternative energy, and homeland security.”
Stoddart, his collaborator James R. Heath, the Elizabeth W.
Gilloon Professor of Chemistry at the California Institute of Technology, and
their research teams report the work in the January 25
issue of the journal Nature. The research was funded primarily by the
National Science Foundation and the Defense Advanced Research Projects Agency.
quote: Also realize my source for the budget information doesn't itemize. So that 420 billion is for ALL DoD operations....training, equipment/weapons, administrative personnel, everything.
quote: quality on quantity.
quote: stop telling us, you are the good guys, all here for the rescue of those poor little europeans ... this storry is starting to get really old. there wouldn't be anything to defend from if your nation hadn't startet messing things up for a few cents per barrel!