Science > Physics > New Diode Could Enable Faster, More Efficient Electronics
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Science > Physics |
| User: |
"Dr. Jai Maharaj" |
| Date: |
16 Oct 2003 07:27:36 PM |
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New Diode Could Enable Faster, More Efficient Electronics |
New Diode Could Enable Faster, More Efficient Electronics
Ohio State University
http://www.acs.ohio-state.edu/units/research/
Science Daily
Thursday, October 16, 2003
Columbus, Ohio - Engineers have designed a new diode that
transmits more electricity than any other device of its
kind, and the inspiration for it came from technology
that is 40 years old.
Unlike other diodes in its class, called tunnel diodes,
the new diode is compatible with silicon, so
manufacturers could easily build it into mainstream
electronic devices such as cell phones and computers.
Industry has long sought to marry tunnel diodes with
conventional electronics as a means to simplify
increasingly complex circuits, explained Paul R. Berger,
professor of electrical engineering and physics at Ohio
State.
"Computer chips now are worse than the Los Angeles
freeway, with wires running back and forth clogging the
path of propagating signals," Berger said. "At some
point, things are going to come to a grinding halt, and
chips won't run any faster."
Because this diode can replace some of the circuits on a
typical chip, it could potentially simplify chip design
without compromising performance.
"Essentially, manufacturers would get more bang for their
buck," Berger said.
Researchers around the world have toiled for decades to
develop such a diode, which could enable fast, efficient
electronics that run on low-power batteries by requiring
fewer devices to perform the same function.
The new diode conducts 150,000 amps per square centimeter
of its silicon-based material -- a rate three times
higher than that of the only comparable silicon tunnel
diode.
Berger designed the diode with a team of engineers from
Ohio State, the Naval Research Laboratory, and the
University of California, Riverside. They describe it in
today's issue of the journal Applied Physics Letters.
"Our goal was to develop a tunnel diode that could be
built directly onto a traditional computer chip at
minimal cost," Berger said. "And we've achieved that."
Tunnel diodes are so named because they exploit a quantum
mechanical effect known as tunneling, which lets
electrons pass through barriers unhindered. The first
tunnel diodes were created in the 1960s, and led to a
Nobel Prize for physicist Leo Esaki in 1973.
Since then, in an effort to build more powerful diodes,
researchers have increasingly turned to expensive, exotic
materials that aren't compatible with silicon, but allow
tailored properties not often available in silicon.
Most modern tunnel diodes are "intraband" diodes, meaning
they restrict the movements of electrons to one energy
level, or "band," within the semiconductor crystal. But
the Esaki tunnel diodes were "interband" diodes -- they
permitted electrons to pass back and forth between
different energy bands.
At first, Berger's team tried to develop intraband diodes
with silicon technology. But faced with what he called a
"materials science nightmare," they turned instead to
Esaki's early tunnel diode technology for inspiration.
To construct a powerful interband diode, Berger's team
had to develop a new technique for creating silicon
structures that contain unusually large quantities of
other chemical elements, or dopants, such as boron and
phosphorus.
"Essentially, we traded one nightmare for another,"
Berger said with a laugh. "Mother Nature doesn't want
that much dopant in one place, but the doping problem was
one that we felt we could tackle."
They layered silicon and silicon-germanium into a
structure that measured only a few nanometers, or
billionths of a meter, high. Then they discovered that by
changing the thickness of a central "spacer" layer, where
the electrons are tunneling, they could tailor the amount
of current that passed through the material. This had to
be tempered with a design that kept the boron and
phosphorus from intermixing.
Berger said that the diode's ability to operate in low-
power conditions makes it ideal for use in power-hungry
devices that generate radio-frequency signals, such as
cordless home telephones and cell phones. With little
power input, the diode could generate a strong signal.
One other application that Berger finds particularly
interesting involves medical devices. The diode could
support a low-power data link that would let doctors
perform diagnostics on pacemakers and other implants by
remote, without wires protruding through a patient's skin
that could cause infections.
Co-authors on the paper included electrical engineering
graduate students Niu Jin, Sung-Yong Chung, and Anthony
T. Rice, and physics graduate student Ronghua Yu, all of
Ohio State; Phillip E. Thompson of the Naval Research
Lab; and Roger Lake of the University of California,
Riverside.
This work was sponsored by the National Science
Foundation and the Office of Naval Research. Berger will
continue work supported by NSF and a major electronics
company to develop wireless applications for the
technology. Depending on that initial development, the
technology could reach consumers anywhere from five to 15
years from now.
- - -
This story has been adapted from a news release issued by
Ohio State University.
Source - http://www.sciencedaily.com/releases/2003/10/031015030916.htm
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Posted on Thursday, October 16, 2003 by sourcery
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Britney's Guide to Semiconductor Physics
http://britneyspears.ac/lasers.htm
Britney's Band theory
http://britneyspears.ac/physics/basics/basics.htm
Posted on Thursday, October 16, 2003 by Diogenesis
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Don't get too excited -- the work-horse of
microelectronics is the transisor, not the diode.
Posted on Thursday, October 16, 2003 by expatpat
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a di Ode to a Nightingale?
http://eir.library.utoronto.ca/rpo/display/poem1131.html
Posted on Thursday, October 16, 2003 by sourcery
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OK diode sounds old fashioned, like vaccuum tubes
They should call it something like Quantam Laser Enabling
Embed
Posted on Thursday, October 16, 2003 by GeronL
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