|
|
|
|
![1105 Media [justice]](/images/ds1_pntmlogo.gif "1105 Media [justice]") |
 |
|
|
|
|
|
home > April 21, 2008 issue > article
USAF spends on flexible microcircuits
By Kevin Fogarty
Special to Defense Systems
The Air Force Office of Scientific Research at Wright-Patterson
Air Force Base, Ohio, has announced it is funding research on thin,
flexible transistors that could be developed into high-performance
optoelectronics for high-speed photography, high-performance antennae
that could be applied to the skin of aircraft and other innovative
uses.
The researchers, led by Zhenquing Ma and Max Lagally of the University of Wisconsin-Madison developed a technique to create
highly flexible semiconductors that are able to withstand impact and
severe vibration and run at 7 GHz, rather than the current standard,
0.5 GHz.
Part of the performance improvement comes from the tendency of silicon-based semiconductors to run faster after being stretched — a technique
semiconductor manufacturers already use.
Rather than etching semiconductors into rigid substrates of insulated silicon
— on which normal microchips are based — the flexible versions are
built from a three-layer nanofabric of silicon and silicon-germanium, laid on a base of silicon dioxide.
The chip is then dipped in an acid bath to dissolve the oxide and leave a molecules-thick nanomembrane that is stretchable, bendable and runs at much higher frequencies than it would have in a rigid structure. The team
needs to find a more economical way to produce and separate the flexible
membranes and produce chips larger than about a centimeter square.
Previous methods required researchers to manually create breaks in the
crystalline structure of the silicon that could act as spacers or hinges to
allow the chip to bend. That method is painstakingly slow, however.
The researchers envision low-power flexible electronics wrapped
around irregular-shaped objects to act as 360-degree antennae or sensors
for light and motion. A laser can read bent circuits more quickly
than flat versions, for example, by reaching all points on the circuit’s
curve from a single position,rather than having to scan the whole circuit
as is now common.
Because germanium reacts much more efficiently to light than regular
silicon, silicon-germanium chips have the potential to be two to three
times more sensitive in light-sensor and photography applications than
current chips.
Researchers at Stanford University, UCLA, the Energy Department’s
Argonne National Laboratory and the University of Illinois at Urbana-
Champaign are working on similar approaches.
|
|
|
|
|
|
|
