January/February 2018 Marine Electronics Journal 41
together with their infrastructure support. The
total SiC device market is expected to reach $1
billion USD in 2022.
Gallium nitride (GaN)
GaN is a newer member of the wide
bandgap fraternity. Gallium nitride, however,
has a bit of a head start, being a proven and
reliable technology for radar applications, but
more about that later. Its higher critical operating voltage strength and higher electron mobility enables GaN devices to have a smaller size
for a given application than conventional silicon. And, most importantly, it’s superior to SiC
in terms of transistor operating speeds.
No one is suggesting that all conventional
silicon-based devices will be replaced by SiC or
GaN, but some displacement of silicon by
either SiC or GaN has already begun. A brief
look at Johnson’s Figure of Merit for transistors
(see below) helps us narrow the field of applications suitable for SiC and GaN. Johnson’s
Figure of Merit is a measure of the suitability of
semiconductor materials for high-frequency
power transistor applications based on the
material properties listed. As you can see it
highlights the greater suitability of GaN over
SiC for higher frequencies.
GaN transistors have been widely used in
military grade radars since 2015. Raytheon, a
believer in GaN, touts itself as the only company to have its own GaN foundry (in
Andover, MA) that builds ICs. Jim Bedingfield,
Missile Defense Director at Raytheon, says that
replacing traditional GaAs with GaN can
increase radar’s range by 50%, improve its ability to discriminate between targets or increase
its volume of coverage by five fold. They chose
to use GaN in their contract for new and re-engineered Patriot air missile defense radars.
These were followed by the Army/Navy
AN/TPY- 2 transportable surveillance radar and
the AMDR radar for the Navy’s Arleigh Burke
destroyer in 2016 and Northrop Grumman’s
AN/TPS-80 and Lockheed Martin’s AN/TPS-
77s that same year.
Down the road
Diamond is known in some circles as the
ultimate wide bandgap semiconductor material. It has the widest bandgap of all such materials, the highest dielectric constant, the highest breakdown field and the highest carrier
mobility. I know, I know, what about cost?
Considering diamond’s status as a luxury gemstone, the idea of integrating it with electronics
may appear expensive. Not to worry.
According to Adam Khan, founder and
CEO of SKHAN Semiconductors, “AKHAN
Semiconductor has overcome this hurdle by
developing a state-of-the-art manufacturing
process that takes common methane gas as
the input and produces the perfect diamond
wafers, which can then be used as a platform
for fabricating semiconductor devices.” So,
hang in there—we don’t know exactly when,
but it’s likely to show up on the bridge sooner
rather than later. MEJ
Johnson’s Figure of Merit is a measure of the suitability of semiconductor materials for high-frequency
power transistor applications and requirements. It is the product of the charge carrier saturation velocity
in the material and the electric breakdown field under identical conditions.
Bandgap is the difference between the top of the valence band and the bottom of the conduction band
measured in electron volts (eV).
Courtesy of Creative Commons Usage
Source: Evince Technology Ltd. Applied Diamond Electronics
About the author
Ev Collier is an electrical engineer, an avid cruising sailor and amateur boat builder. He was
most recently director of technology for the Precision Materials Group at GTE. Collier is a
member of the Society of Naval Architects and
Marine Engineers, the American Boat & Yacht
Council and National Association of Corrosion
Engineers, and the author of The Boatowner’s
Guide to Corrosion.