October 2000 Newsletter - Naval Postgraduate School

RAD-HARD SEMICONDUCTOR CHIPS, continued from page 49
was the first to measure in-situ and characterized “soft
errors” during the operation of a 20 GHz circuit. The
technique was first show with Hughes’ digital InGaAs
Hetrojunction Bipolar technology and additional work
continues with AFRL, MIT-LL and SPAWAR.
(Weatherford/Fouts)
• 1998 – Present: NPS has a unique relationship with
Silvaco International, a Santa Clara firm that develops
“Virtual Fab” software. We have the capability to simulate
the IC fabrication process, electrically characterize it, and
irradiate the “virtual device” in software to understand
effects. It is also faster and safer than designing and
performing experiments, however experiments are required
to verify the computer models. Further simulation analysis
can study new transistor structures or materials to increase
radiation hardness. Present work supports the SPAWAR
San Diego Silicon-on-Insulator Foundry, with cooperation
from Dynamic Research Corporation, and Vanderbilt
University. (Weatherford)
• 1999 – Present: Projects with Draper Labs to study
displacement damage in photodetectors for the Trident
program. (Weatherford)
• 1999 – Present: Projects with NSWC Crane to investigate
radiation susceptibility of new generation rad-hard power
transistors (Ciezki/Ashton)
• 1994 – 99: Projects with NRL, SPAWAR to design lowpower
logic families in GaAs IC technologies for rad-hard
environments. Professor Fouts received a patent on his
THE “LINAC,”continued from page 49
extended to other heavy nuclei as far as lead and uranium.
Almost from the beginning, the effects of radiation was
investigated on various systems as diverse as semiconductors,
polymers, and later, the recently discovered high temperature
superconductors. The investigations of semi-conductors and
devices were aimed at measuring the radiation levels causing
degradation, to anticipate effects of either space radiation or
nuclear detonations. The unexpected result for some high
temperature superconductors was an actual enhancement of
some properties after irradiation.
The electron beam from the LINAC may be used to
produce electromagnetic waves by various distinct mechanisms.
Transition radiation occurs when the electrons pass a
boundary, such as a metal or plastic foil, and this radiation
occurs in the radio frequency optical and x-ray regions.
RESEARCH CENTER
inventions in this area. (Fouts)
• 1997 – Present: Study and analysis of silicon based
CMOS technologies for total dose radiation effects for
proprietary NSA integrated circuits. This work has lead
to new IC layout procedures and has been extended into
a software tool with Lockheed-Martin to design integrated
circuits for weapon environments. (Fouts)
• 1995-Present – Modeling and analysis of InP, GaAs and
Si solar cells for space applications, supported by both
AFRL and NRL in investigating degradation in solar cells
and in operational amplifiers. (Michael)
Shown above are only a few research projects, many
opportunities exist in this field, from the design of rad-hard
circuits and systems, analysis and testing of components for
present systems, to the future modeling of next generation
semiconductor technologies. The organization of a
multidisciplinary center at NPS in areas of electrical engineering,
space systems, materials engineering, and physics to
support DoD in this critical technology area should help
focus continued and new support from outside the NPS
while providing an important service to the strategic and
space communities.
Just remember next time you get upset at your laptop
hanging up in a cross-country flight, or your new 1 GHz
high performance desktop gets hungup, you may need to buy
some rad-hard chips, not reinstall Windows©. Hopefully our
future defense systems designers will be able to acquisition
rad-hard parts in the future.
Experiments here were aimed at soft x-ray productions from
single and multiple foils.
Cerenkov radiation occurs if the electrons exceed the speed
of light that can only occur in a medium even air. Coherent
Cerenkov radiation was observed in which the many electrons
in a bunch generated by the LINAC radiate together
and reinforce.
Another phenomenon called parametric x-rays (PxR) was
measured. Here x-rays are produced when the electron
passes through a crystal. Typical crystal spacings result in 5
to 10 kilovolt x-rays.
Over the years the facility has been used for various
projects, and oddly enough in recent years the research is
going back to its roots, studying radiation effects in semiconductors
for strategic systems.
NPS Research page 50
October 2000