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Review of wide band-gap semiconductors technology
Haiwei Jin
1
, Li Qin
1
, Lan Zhang
1
, Xinlin Zeng
1
, Rui Yang
1
1
Library, China Defence Science and Technology Information Center, china
Abstract.Silicon carbide (SiC) and gallium nitride (GaN) are typical representative of the wide band-gap
semiconductor material, which is also known as third-generation semiconductor materials. Compared with the
conventional semiconductor silicon (Si) or gallium arsenide (GaAs), wide band-gap semiconductor has the wide band
gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable
semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation
environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology
research in various countries. This article describes the research agenda of United States and European in this area,
focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing
challenge of the wide band-gap technology.
1 INTRODUCTION
Widely used of semiconductor technology in various
military fields broke the traditional concept formed in
thousa-
nds of years that weapons equipment’s advantage is only
the size, the number and the more of massive destruction,
so that system of weapons become smaller, lighter, less
power wasted, higher reliable, stronger operational
effective and powerful. Military electronic equipment
required to operate at high temperature, high radiation and
other harsh environments, can detect small targets of
long-distance and real-time process high-speed sensor
data, and the operating frequency band beyond the
ordinary commercial range. Thus, require for the military
electronic equipment for semiconductor components is
much higher than ordinary electronic equipment, its safety
and reliability of components must be higher. It is worth
noting that, using conventional semiconductor technology
to produce electronic systems has been unable to meet the
requirements of next generation military applications for
volume, weight and higher reliability. Wide band-gap
semiconductor device has advantage of high frequency,
high power, high temperature and potential of resistance
to harsh environments, so that provides a method to solve
these problem.
Semiconductor of band gap greater than 2.2eV is defined
as the wide band-gap semiconductor (WBGS), typical of
wide band-gap semiconductor materials are silicon
carbide (SiC) and gallium nitride (GaN), these
semiconductor materials are also known as third-
generation semiconductor material. In comparison with Si
and GaAs as the representative of the second generation
of semiconductor, wide band gap semiconductor has
merits of wide band gap, high saturated drift velocity,
high critical breakdown electric field. in order to highlight
the advantages compared to Si and GaAs as the
representative of the second generation of semiconductors.
In recent years, as SiC single crystal growth technology
and GaN Hetero-epitaxial technology continue to mature,
wide band-gap semiconductor power device’s
development and application rise rapidly.
Figure 1. Wide band gap materials and their forbidden band
width
In the start-up and push of wide band-gap semiconductor
technology program (WBGSTI) of US Defense Advanced
Research Projects Agency, many other research projects
of Europe ESCAPEE and Japan NEDO, SiC, GaN and
other wide band-gap semiconductor materials and devices
research gained rapid development; a number of interna-
tional semiconductor manufacturers have introduced high-
power, high-frequency, high-temperature wide band-gap
semiconductor products, whose applications are con-
DOI: 10.1051/
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MATEC Web of Conferences
stantly expanded. In short, American and European coun-
tries will always put wide band-gap semiconductor tech-
nology on an extremely important strategic position, hesi-
tate to invest heavily to implement a number of wide band
gap semiconductor technology development plan in order
to enhance the ability of military equipment, and have
achieved good results. This article described the devel-
opment of major initiatives in Europe and America in a
wide band-gap semiconductor technology and the latest
progress in the development and research in the device. It
focused on the wide band-gap semiconductor technology
development plan implemented in US, Europe and other
developed countries and the far-reaching impact on mili-
tary or other important facilities produce, summed up the
facing challenge of the wide band-gap technology.
2 AMERICAN WIDE BAND-GAP
SEMICONDUCTOR TECHNOLOGY
United States was the first country to start the wide band-
gap semiconductor technology research, and many well-
known universities and research institutions, such as Ray-
theon, TriQuint, BAE, MIT, Cree, put a lot of manpower
and material resources in the technology, and their re-
search is most outstanding. DARPA hesitated to invest
huge amounts of money to implement a number of wide
band-gap semiconductor device and circuit technology
development plans. DARPA aimed to enhance military
radar, submarines and various other systems and equip-
ment performance and reliability operated in harsh envi-
ronment, and solved a number of technical bottlenecks of
wide band-gap technology currently facing.
It is worth noting that, so far the largest investment, the
largest participating institutions, the results of the most
prominent and most influential program is counted the
wide band-gap semiconductor technology initiative
(WBGSTI), which launched by DARPA in 2002, lasted
eight years, divided in three stages; the first phase from
2002 to 2004, focused on material development, achieve
commercialization of 2-4 inches SiC substrate material,
has been completed now; the second phase from 2005 to
2007, focused on device development, used wide band
gap semiconductor material to product and demonstrate
the RF power amplifier for improving its power-added
rate, bandwidth and power density, ultimately achieved
high-volume production of high reliability, high-
performance microwave and millimeter-wave GaN-based
devices; the third stage, from 2008 to 2009, developed
GaN-based high reliable, high performance MMIC
(monolithic microwave integrated circuit), and test their
applications in a number of modules; this program cost
hundreds millions of dollars.
Figure 2. Six inchs silicon carbide crystal and single crystal
substrate
With the support of DARPA, Raytheon achieved the
world advanced level in the wide band-gap technical field,
such as the first GaN MMIC produced by Raytheon;
completed a historic first X- band GaN T / R (transmitter /
receiver modules) verification, it included with a range of
operating conditions, widely and successfully designed a
confirmatory test to verify the GaN technology maturity,
on this basis, completed a historic first X- band GaN
TRIMM (final transmitter / receiver multichannel integra-
tion module) verification, confirming the GaN perform-
ance under the relevant operating conditions, including
extensive tests in a relevant combination work environ-
ment, which including a operation test for a trial GaN
array at 1000 hours in a laboratory, and conducted GaN
array insert verification tests in a production radar, ready
for TRIMM into the production stage, as a milestone in
the success of the second phase of the WBGS project task;
in 2013 due to successful completion of the Defense Pro-
duction Act Title ċ GaN production improvement pro-
jects, it rewarded by office of the Secretary of Defense;
through this project Raytheon’s GaN production has in-
creased at least 300 percent, the cost of monolithic mi-
crowave integrated circuits decreased at least 75%. Cur-
rently GaN has become the Raytheon Company’s core
competitiveness, as well as technology pillars behind the
major project, such as air, missile defense radar and the
Next Generation Jammer. In 2014 Raytheon successfully
demonstrated the active electronically scanned array
(AESA) and gallium nitride (GaN) technology prototype
at the US "Patriot" anti-missile air defense radar system.
This technology enables 360 degree sensing coverage in
the future; it will expand the scope of defense, and to re-
duce the time of detection, identification and threat elimi-
nation. AESA technology based GaN will further improve
reliability of the "Patriot" radar and decreased life-cycle
costs.
Figure 3. GaN MMIC developed by Raytheon Company for
completing the second phase of WBGS
TriQuint Semiconductor, Inc. is a leader of GaN HEMT
developed field, with the highest level of technology in
the development of GaN alternative substrates, S-band
and X-band GaN MMIC application has achieved excel-
lent system performance. According to reports, the wide
band-gap semiconductor SiC JFET has been able to re-
place conventional Si IGBT module in the US Navy's
next-generation electric ships, such as DDG1000 systems.
System simulation results show that, with the wide band-
gap semiconductor SiC, replacing Si, many system pa-
rameters have been greatly improved. System power con-
sumption can be reduced to 1/25 of the original system;
switching speeds improved 100 to 200 times than the past.
In 2010, TriQuint Semiconductor, Inc. began to partici-
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pate in third phase project of the WBGS; in May 2014 it
developed the device whose mean work time is more than
106 hours between failures at 200 ° environment, made
the successful completion of the third phase of the task.
Base the research, many wide band-gap semiconductor
devices were developed for radar.
Figure 4. Wide band gap device for radar
SiC power modules developed by Cree. will be exten-
sively used on the new aircraft of US Air Force F-
35LightingII. In power system applications, the efficiency
of the power device is higher, the advantages of system
will be more prominent, and reduce of carbon emissions
is one of the obvious advantages. According to the differ-
ence of application areas, it will also bring many other
benefits. If the wide band-gap power electronic devices
are used in hybrid electric locomotive, DC battery power
can be more efficiently converted to AC source; that can
more effectively drive the engine and reduce energy con-
sumption. Moreover, the heat dissipation of electronic
components will be reduced, so that the cooling system
will be smaller, lighter, less complex, and ultimately re-
duce the production cost, save package space, and achieve
energy saving purpose. Improving the device efficiency
may also bring a series of advantages for military aircraft
and alternative energy systems, such as improving effi-
ciency can reduce weight, reduce the requirements for the
cooling system, which can extend and expand the flying
distance and range of the aircraft.
Figure 5. F-35 ‘s radar and SIC power components
As a leader in wide band gap technology, the United
States has developed wide band-gap devices; in 2014, the
M/A-COM Company has developed a new SiC-based
GaN HEMT device, named MAGX-001214-650L00, this
transistor operates in the L-band, 650W peak power, can
reliably operate at 50V or even more extreme load adapt
conditions. This device is shown in Fig.2.
Figure 6. M / A-COM's power devices
In 2014, United States CREE Company also developed
the CGHV1F006S and CGHV1F025S two power devices,
two devices are the largest power continuous wave GaN
HEMT in the field, use dual flat no-lead package.
CGHV1F006S operating frequency covers DC-18GHz,
output power is 6W; CGHV1F025S operating frequency
covers DC-18GHz, output power is 25W.
Figure 7. CREE Company developed two power devices
3 EU WIDE BAND-GAP
SEMICONDUCTOR TECHNOLOGY
The EU’s military application intention of development
wide band-gap technology is clear, in order to improve air
defense surveillance radar and performance of the high
RF wireless communication system, the EU focuses on
efficient 1 ~ 40GHz frequency range, high power, high
linearity and low cost single chip amplifier. The EU has
developed the KORRIGAN plan, which is a five-year
development plan in order to develop GaN HEMT tech-
nology in 2005. The EU hopes through carrying out the
plan to make the European Union to form a complete in-
dustrial chain of wide band-gap semiconductor technolo-
gy, which can contribute positively to the development
and application of wide band gap semiconductor technol-
ogy.
Seven countries of France, Italy, Netherlands, Germany,
Spain, Sweden and the United Kingdom participate in
KORRIGAN plan. Units participated the plan covers the
technical field of materials research, circuit design, mod-
eling studies, process control, reliability evaluation, heat
treatment and packaging. In order to successfully achieve
program objectives and develop advanced GaN technol-
ogy in 2009 in accordance with established goals,
KORRIGAN plan designed demonstration system specifi-
cally to verify the validity of GaN technology in a variety
of applications, including S-band high-power amplifiers,
X-band broadband high-power amplifiers, low noise am-
plifiers and switches. In support of the EU government,
the plan goes smoothly. Thus, in recent years the EU has
made fruitful results in GaN HEMT devices and micro-
strip MMIC amplifiers research, performance of devices
and circuits continues to improve, many technology level
is highest in the world.
Figure 8. Germany developed GaN HEMT devices
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In 2010, under the leadership of the European Defence
Agency, Germany, France, Italy, Sweden and the United
Kingdom jointly launched "manufacture SiC substrate
based GaN devices and GaN epitaxial layer wafer supply
chain" (MANGA) project, the project aimed to optimize
GaN-based power electronics R & D and manufacturing,
the project major research the GaN-based transistor layer
epitaxial grown on newly developed SiC substrate, by
using the existing OEM technology, these transistor layer
are used in the manufacture of entirely European produc-
tion HEMT. In the case of not depend on international
suppliers, the EU five countries jointly developed a high-
quality GaN-based electronic devices, in 2014, the Euro-
pean Defence Agency declared that it has successfully
established the supply chain for Europe GaN-based power
electronics.
Saab Company has begun to develop GaN technology
since 2005. The company will use GaN devices in its new
Gripen active electronically scanned array (AESA) radar
system. In May 2014, Saab Company announced the ap-
plication scope of its Gripen active electronically scanned
array radar system, including X-band and S-band three
types land-based systems and two types sea-based sys-
tems. According the announce of Saab company , Gripen
active electronically scanned array radar system 4A me-
dium-range version and 8A remote version are first batch
of GaN complete two-dimensional system applied to a
three-dimensional AESA multi-function radar, capable of
simultaneous air defense, air surveillance and Weapon
Locating.
Figure 9. The SIC device of Infineon Company
Figure 10. Gripen’s active electronically scanned array radar
system
4 FACING CHALLENGE OF WIDE BAND-
GAP TECHNOLOGY
4.1 Material immature or defective
SiC single crystal material defect exists, then reduce and
eliminate the defect density, and the increase of single-
wafer size have become focuses of research. In recent
years, great progress has been made in the respect of re-
duction and eradication of fatal flaw microtubule density,
which result the SiC power semiconductor performance
and reliability decrease; Cree company began to supply 4
inches SiC single wafer of Zero Micropipes density in
2007. GaN material is immature, material defects results
the critical breakdown field decline, Buffer substrate
leakage of electricity is one of the main reasons of GaN
power devices cannot reach the material theoretical limit.
4.2 Reliability issues
Two major technical difficulties of SiC devices have not
been completely broken through: low inversion layer
channel mobility and gate oxide reliability under high-
temperature and high electric field. Through a special gate
oxidation process, SiC / SiO2 interface defects can be
eliminated to improve the inversion layer channel mobil-
ity. For SiC BJT power devices, now an urgent need to
address is the current gain degradation. The reasons of
instability caused by the current gain are still unclear; one
reason possibly is due to the stacking fault caused the
epitaxial base region. Reliability issues exist in GaN de-
vice; trap, material defects, surface treatment and passiva-
tion layer protection, Buffer substrate leakage, degrada-
tion of Schottky gate metal under high voltage and high
current and high field, insulated gate dielectric and sur-
face charge and other issues impact the GaN device reli-
ability.
4.3 Packaging issues
There are packaging problems in high-temperature, high-
power SiC, GaN device. When SiC, GaN materials and
processes problems are basically solved, Reliability issues
of the device package will rise as the main factor impact-
ing the high temperature high-power SiC, GaN device
performance. Especially GaN, with equal level of power
density of SiC, but the thermal conductivity is lower than
SiC; thus it exacerbates the problem of thermal spreading
of GaN device, and puts forward a more serious challenge
for high power GaN device package.
5 CONCLUSION
As the core technology of electronic, intelligence, integra-
tion and miniaturization of a new generation weapon, the
third generation of semiconductor, that is wide band-gap
semiconductor technology gets special attention of US,
Japan, the European Union and other developed countries,
for its set of advantages of small size, light weight, good
stability, high reliability, low power consumption and so
on. A number of wide band-gap semiconductor technol-
ogy development programs implemented in these coun-
tries will make the wide band-gap semiconductor technol-
ogy research continue to rise to new levels, so that a vari-
ety of wide band-gap semiconductor devices become sat-
ellite communications, high-speed computers, precision-
guided, early warning and detection, intelligence and re-
connaissance, electronic warfare, intelligent fire control
systems and other military equipment’s necessary and
important components.
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