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Impact of Wide Bandgap Semiconductors on Power
Electronics: Challenges and Opportunities
Md. Arifur Rahman
Abstract
Wide Bandgap Semiconductors (WBGs) have
emerged as a disruptive force in the realm of
power electronics, reshaping the way we
generate, convert, and manage electrical energy.
This abstract delves into the profound impact of
WBGs on power electronics, revealing the
myriad of advantages they bring to the table.
These advantages include enhanced energy
efficiency, miniaturization of devices, and the
ability to operate at higher frequencies, ushering
in a new era of power electronics innovation.
However, the ascent of WBGs is not without its
challenges. This abstract explores the hurdles
such as cost-effectiveness, ensuring reliability in
demanding conditions, and seamlessly
integrating WBG devices into existing systems.
These challenges are pivotal in understanding the
path forward for WBG technology.
Despite these challenges, the abstract highlights
the abundant opportunities that lie ahead. WBGs
have the potential to revolutionize industries like
electric vehicles, renewable energy, and data
centers, contributing to reduced energy
consumption and a more sustainable future. As
research and development efforts continue, the
promise of WBGs as a cornerstone of the next
generation of power electronics becomes
increasingly clear.
In essence, this abstract offers a glimpse into the
dynamic landscape where Wide Bandgap
Semiconductors intersect with power electronics,
shaping the future of how we harness and
distribute electrical power while addressing the
challenges and embracing the opportunities
presented by this groundbreaking technology.
Introduction
The field of power electronics stands at the heart
of modern electrical systems, serving as the
pivotal bridge between electricity generation,
distribution, and utilization (Baliga, 1996). It
plays a critical role in the efficient conversion,
control, and management of electrical energy,
impacting various sectors ranging from
transportation and renewable energy to consumer
electronics. Recent advancements in
semiconductor technology have introduced a
transformative element into the realm of power
electronics—the advent of Wide Bandgap
Semiconductors (WBGs) (Shenai et al., 2018).
This introduction explores the profound
implications of WBGs on power electronics,
shedding light on their benefits, challenges, and
the boundless opportunities they offer.
Historically, silicon (Si) has been the primary
semiconductor material of choice in power
electronics due to its well-established properties
and manufacturing infrastructure. However, as
the demands for higher energy efficiency, greater
power density, and increased operating
frequencies have grown, the limitations of silicon
have become increasingly apparent. Silicon-
based devices have inherent constraints related to
energy loss, heat generation, and switching
speed, rendering them suboptimal for emerging
applications requiring superior performance.
Wide Bandgap Semiconductors, such as Silicon
Carbide (SiC) and Gallium Nitride (GaN), have
emerged as a disruptive force, challenging the
dominance of traditional silicon-based devices.
These materials possess unique electronic
properties, including wider energy bandgaps,
higher electron mobility, and superior thermal
conductivity, which endow them with distinctive
advantages over silicon.
Silicon Carbide (SiC), with a bandgap of
approximately 3.26 eV, and Gallium Nitride
(GaN), with a bandgap of around 3.4 eV, exhibit
substantially wider bandgaps than silicon's 1.1
eV. This characteristic allows WBGs to handle
higher voltages, operate at elevated temperatures,
and achieve lower on-resistance, resulting in
reduced energy losses and improved energy
efficiency. Moreover, their higher electron
mobility enables faster switching speeds, making
them suitable for high-frequency applications.
The implications of these properties are far-
reaching. WBGs have the potential to
revolutionize power electronics across various
sectors. However, the path to realizing these
opportunities is not without obstacles. Challenges
such as cost-effectiveness, reliability in harsh
environments, integration into existing systems,
and standardization efforts must be addressed to
fully harness the potential of WBG technology.
This introduction sets the stage for a
comprehensive exploration of the impact of Wide
Bandgap Semiconductors on power electronics. It
serves as a foundation for understanding the
benefits and challenges associated with WBGs
and the strategies to overcome these challenges.
The subsequent sections delve deeper into the
physics, applications, benefits, challenges, and
future prospects of WBGs in the realm of power
electronics, offering valuable insights into the
transformative potential of this groundbreaking
technology.
2. Wide Bandgap (WBG) Semiconductors: Physics and Properties
2.1 Why Not Silicon
Higher Operating Temperatures
Higher Switching Frequencies
Reduced Power Losses
Miniaturization
High Voltage and High Power
Applications
2.2 Why WBG Semiconductors
Higher Efficiency
High-Temperature Operation
Higher Voltage Ratings
High-Frequency Operation
Reduced Size and Weight
Improved Power Density
Fast Switching Speed
Longer Device Lifetimes
Reduced Cooling Requirements
Emerging Applications
Wide bandgap semiconductors are a sub-class of
semiconductor materials, defined by their larger- than-Si bandgap, typically between two and four
electron volts (eV). There are several wide
bandgap materials currently being explored for
power conversion: silicon carbide (SiC), gallium
nitride (GaN), gallium oxide (Ga2O3) aluminum
nitride (AlN), and diamond. Of these, diamond-
based devices are considered by many to hold the
most promise but are hindered by small wafer
size, scalability issues, and cost (Burak Ozpineci,
Chinthavali, and Tolbert 2006).
While SiC and GaN also have more crystal
growth problems than Si, manufacturers have
been able to grow large crystals of these
materials. Because of this, Ga2O3, AlN and
diamond power devices are all extremely
primitive in development, while SiC and GaN-
on-Si are both on the market and bulk GaN is in
development today.
Fig. 1: Comparison properties of various semiconductors.
Figure. Relative key properties of semiconductor materials (adapted from Rohm Semiconductor 2013;
Misra, Ramanan, and Lee 2015; Meneghesso et al. 2016; Evans et al. 2016)).
Compared to Si, SiC has a higher breakdown field and thermal conductivity, whereas GaN has a higher
breakdown field and electron mobility. These key material properties lead to higher operating temperatures,
higher endurance to electromagnetic radiation, and a higher operational voltage for a given design.
Table 1: Comparison of wide bandgap materials properties with Si.
Wide bandgap power electronics are a small but
growing segment of PE (Figure 1-8). in 2015, the
technology information company IHS estimated
that the market for PE will be nearly $18 billion
in 2016 (Fodale and Eden 2015) while the market
for WBG devices is expected to be less than $300
million (Eden 2016), or less than 2% of the PE
market. Assuming the PE market continues its
current growth rate however, WBG devices can
be expected to comprise over 12% of the PE
market by 2025. This growth is being driven by
demand for smaller packaged electronics with
increased power density and higher efficiency.
Replacing Si with a WBG semiconductor can
yield higher breakdown voltages, faster
switching, lower switching losses, and higher
operating temperatures. Through careful design,
all of the attributes and trade-offs can lead to
power conversion products that have higher
power density (more efficient and smaller),
weigh less and may even cost less.
Figure 2: WBG semiconductors within the power electronics market by revenue, (a) left and
percent (b) right (Fodale and Eden 2015; Eden 2016).
2.3 High Breakdown Voltage
WBG materials offer higher breakdown voltages,
making them suitable for high-power
applications. SiC devices can handle voltages
well above 1,000 V, while GaN devices can reach
up to 650 V. This high breakdown voltage is
essential for designing robust power electronic
systems.
For example, the breakdown voltage (VB) of a pn
diode is expressed in Ref. [1] as follows
Fig. 3: Maximum breakdown voltage of a power device at the same doping density normalized to Si.
2.4 Low On-Resistance
WBG devices exhibit lower on-resistance
(R<sub>ds</sub>) compared to Silicon devices.
This low R<sub>ds</sub> reduces conduction
losses, resulting in higher energy efficiency and
reduced heat generation.
2.5 High Thermal Conductivity
SiC has excellent thermal conductivity, which
helps dissipate heat effectively. GaN also has
good thermal properties. This allows WBG
devices to operate at higher temperatures without
performance degradation.
Where, junction-to-case thermal resistance, Rth-
jc, is inversely proportional to the thermal
conductivity, λ is the thermal conductivity, d is
the length, and A is the cross-sectional area.
Higher thermal conductivity means lower Rth-jc,
which means that heat generated in a SiC-based
device can more easily be transmitted to the case,
heatsink, and then to the ambient; thus, the
material conducts heat to its surroundings easily,
and the device temperature increases more
slowly.
2.6 High Electron Mobility
Both SiC and GaN have higher electron mobility
than Silicon. This property enables faster
switching speeds and higher operating
frequencies, making WBG devices suitable for
high-frequency applications.
2.7 Figure of Merit Comparison
For a comparison of the possible power
electronics performances of these materials, some
commonly known figures of merit are listed in
Table 2.2. In this table, the numbers have been
normalized with respect to Si; a larger number
represents a material’s better performance in the
corresponding category. The figure of merit
values for diamond are at least 40–50 times more
than those for any other semiconductor in the
table. SiC polytypes and GaN have similar
figures of merit, which implies similar
performances.
Silicon and GaAs have the poorest performance
among the semiconductor materials listed in
Tables 2.1 and 2.2, and diamond has the best
electrical characteristics. Much of the present
power device research is focused on SiC. In the
next sections, diamond, GaN, and SiC will be
compared and contrasted with each other.
Table 2: Main figures of merit for WBG semiconductors compared with Si
Where,
JFM: Johnson’s figure of merit, a measure of the ultimate high-frequency capability of the material
BFM: Baliga’s figure of merit, a measure of the specific on-resistance of the drift region of a vertical field
effect transistor (FET)
FSFM: FET switching speed figure of merit
BSFM: Bipolar switching speed figure of merit
FPFM: FET power-handling-capacity figure of merit
FTFM: FET power-switching product
BPFM: Bipolar power handling capacity figure of merit
BTFM: Bipolar power switching product.
Figure 4: WBG power electronics within the semiconductor industry. (Semiconductor Industry Association
(SIA) 2016; IHS Technology 2016; Fodale and Eden 2015; Eden 2016)
3. Applications of Wide Bandgap Semiconductors
Wide Bandgap Semiconductors find applications in various sectors.
Figure 5: Applications of WBG semiconductors in various sectors.
3.1 Electric Vehicles (EVs)
WBG devices are used in EV power electronics
for efficient energy conversion, faster charging,
and improved range. Their high power density
and thermal performance are advantageous in
electric vehicle drivetrains.
3.2 Renewable Energy
SiC and GaN devices are employed in renewable
energy systems, such as solar inverters and wind
turbine converters. They enhance energy
harvesting efficiency and grid integration.
3.3 Data Centers
The high-frequency operation of WBG devices is
beneficial in data center power supplies, reducing
energy consumption and improving server
performance.
3.4 Aerospace and Defense
Some of the requirements for a power converter
in a spacecraft are small mass, small volume, and
high/low temperature operation. The high-
temperature operation capability and lower losses
of WBG semiconductor-based power devices
would provide mass and volume advantages in
these applications. In addition, WBG
semiconductor-based power devices are
radiation-hard, which means that they are less
susceptible to the damaging effects of radiation.
Therefore, use of these devices would allow for
less radiation shielding, which also results in a
gain in mass.
3.5 Power Systems Applications
With the recent advances, power electronics
interfaces to power systems like static transfer
switches, dynamic voltage restorers, static VAR
compensators, high voltage dc (HVDC)
transmission, and flexible ac transmission
systems (FACTS) are getting more and more
attention. Presently, there are no high voltage/
high-current single-Si devices available for these
applications. Instead, lower-rated devices are put
in series and parallel. With the high voltage
capability of WBG semiconductors, in the near
future it will be possible to replace many Si
devices in series and/or in parallel by one WBG
semiconductor-based power device. This will
decrease the device count and the size of these
converters. If single power devices can be used,
balancing resistors and capacitors can be
discarded, saving even more space and avoiding
voltage balancing and/or current-sharing
problems. Moreover, because of the high–
temperature operability and the lower losses of
WBG semiconductor-based power devices,
cooling system size will also decrease. Finally,
with less reverse recovery, fewer or no snubbers
will be required.
4. Benefits and Opportunities
4.1 Energy Efficiency
The superior properties of WBG semiconductors
result in higher energy efficiency, reducing
power losses and ultimately reducing energy
consumption in various applications.
4.2 Miniaturization
WBG devices enable the development of
compact and lightweight power electronic
systems, leading to reduced space requirements
and weight in critical applications like aerospace.
4.3 High-Frequency Operation
Their ability to operate at high frequencies opens
doors for advanced power electronics
applications, such as wireless power transfer and
5G infrastructure.
4.4 Environmental Impact
The increased efficiency and reduced energy consumption associated with WBG technology contribute to
a lower carbon footprint and a greener future.
Figure 6: WBG semiconductor parameter capabilities (blue); physical properties affected by WBG
advantages (red); power electronics characteristics (green); and product benefits (yellow).
5. Challenges in WBG Semiconductors
5.1 Cost
Wide Bandgap Semiconductors are currently
more expensive to manufacture than traditional
Silicon devices, limiting their widespread
adoption.
5.2 Reliability
Reliability concerns, especially in high-
temperature and high-voltage applications, need
to be addressed to ensure long-term performance.
5.3 Integration
Integrating WBG devices into existing power
electronic systems can be challenging due to
differences in voltage and control requirements.
5.4 Standardization
Standardization efforts are required to establish
design guidelines and ensure interoperability
between different WBG device manufacturers.
6. How to overcome these challenges
To overcome the challenges associated with
Wide Bandgap Semiconductors (WBGs) in
power electronics, several strategies and ongoing
research efforts are being pursued. Here are some
ways to address these challenges:
1. Cost Reduction:
a. Economies of Scale: As the production
volume of WBG devices increases, economies of
scale will drive down manufacturing costs.
Continued investments in production facilities
and increased demand from various industries
will help reduce the cost per unit.
b. Improved Manufacturing Processes:
Research into more cost-effective manufacturing
processes for WBG materials, such as SiC and
GaN, can significantly reduce production costs.
c. Material Innovations: Exploring alternative,
cost-effective materials or deposition techniques
for WBGs may lead to more affordable solutions.
2. Reliability Enhancement:
a. Advanced Packaging: Develop improved
packaging technologies that can better dissipate
heat and protect WBG devices from
environmental stressors, ensuring long-term
reliability.
b. Accelerated Testing: Conduct accelerated
testing and reliability studies to identify failure
mechanisms and design more robust devices.
c. Redundancy and Fault Tolerance: Design
power electronic systems with redundancy and
fault-tolerant features to ensure continuous
operation even in the event of device failures.
3. Integration Challenges:
a. Standardization: Develop industry-wide
standards for WBG devices and their integration
into power electronic systems. Standardization
will simplify the design process and ensure
compatibility between components from different
manufacturers.
b. Integrated Solutions: Invest in research and
development efforts to create integrated power
modules that incorporate WBG devices and
associated control electronics, reducing the
complexity of system integration.
c. Compatibility Testing: Rigorously test WBG
devices with various control and driver circuits to
ensure compatibility and optimize performance.
4. Standardization:
a. Industry Collaboration: Encourage
collaboration between semiconductor
manufacturers, power electronics companies, and
regulatory bodies to establish common standards
for WBG devices, packaging, and system
integration.
b. Certification Programs: Develop
certification programs to ensure that WBG
devices meet specific industry standards for
performance and reliability.
c. Educational Initiatives: Promote education
and training programs to familiarize engineers
and designers with the unique characteristics of
WBG materials and their application in power
electronics.
5. Environmental Concerns:
a. Lifecycle Assessment: Conduct
comprehensive lifecycle assessments to
demonstrate the environmental benefits of WBG
devices in terms of reduced energy consumption
and lower greenhouse gas emissions.
b. Green Manufacturing: Emphasize
sustainable and environmentally friendly
manufacturing processes for WBG materials and
devices.
c. Government Incentives: Governments and
regulatory bodies can incentivize the adoption of
WBG technology through policies that promote
energy efficiency and clean energy.
It's important to note that overcoming these
challenges requires a collaborative effort from
industry stakeholders, research institutions, and
government agencies. Continuous innovation,
research, and investment in WBG technology
will play a pivotal role in realizing the full
potential of Wide Bandgap Semiconductors in
power electronics while addressing the associated
challenges.
7. Future Prospects
The future of power electronics lies in the
widespread adoption of Wide Bandgap
Semiconductors. As manufacturing processes
improve and costs decrease, their use will become
more prevalent. The development of standardized
designs and enhanced reliability will further
boost their adoption across industries, resulting in
more energy-efficient and compact power
electronic systems.
8. Silicon carbide (SiC) and gallium nitride
(GaN), who is the future of wide bandgap
(WBG) materials
The future of wide-bandgap (WBG) materials is
likely to involve both silicon carbide (SiC) and
gallium nitride (GaN), as each material has
unique advantages and is better suited to specific
applications. The choice between SiC and GaN
depends on the requirements and constraints of
the application. Here's a brief overview of the
strengths and typical applications of each
material:
Silicon Carbide (SiC):
High Voltage and Power Applications: SiC is
known for its high breakdown voltage and
excellent on-resistance, making it well-suited for
high-voltage and high-power applications. This
includes power inverters for electric vehicles,
renewable energy systems (solar and wind), and
high-voltage DC transmission systems.
High-Temperature Operation: SiC devices can
operate at very high temperatures without
significant degradation, making them suitable for
applications in harsh environments, such as
aerospace and downhole drilling.
Mature Technology: SiC technology is
relatively mature and has been in use for a longer
time compared to GaN, which means that there is
a well-established supply chain and
manufacturing processes. Gallium Nitride (GaN):
Figure 7: Silicon Carbide (SiC) Application Market Trend
Gallium Nitride (GaN)
High-Frequency and High-Speed Operation:
GaN is known for its extremely fast switching
speeds, making it ideal for high-frequency
applications. It is used in RF (radio frequency)
amplifiers, 5G wireless infrastructure, and high-
frequency power converters.
Compact and Lightweight: GaN devices are
smaller and lighter than their SiC counterparts,
which is beneficial for space-constrained
applications like portable electronics and
compact power supplies.
Emerging Technologies: GaN is at the forefront
of emerging technologies, such as advanced radar
systems, satellite communications, and compact,
high-efficiency power converters.
Lower Cost for Some Applications: GaN
devices can be more cost-effective than SiC in
certain lower-power and medium-power
applications.
Figure 8: Gallium Nitride (GaN) Application Market Trend
In summary, SiC and GaN each have their own
strengths and niches. SiC is favored for high-
power and high-voltage applications, while GaN
excels in high-frequency and high-speed
applications. The future of WBG materials is
likely to see continued advancements in both SiC
and GaN technology, with each material serving
specific market segments and applications where
its unique characteristics are most beneficial.
It's important to note that ongoing research and
development in both materials are driving
improvements in performance, cost, and
manufacturability, which will continue to expand
their applications in the future. The choice
between SiC and GaN will depend on the specific
requirements and priorities of each application.
In addition, SiC has much better electrical
properties than Si and similar to GaN. These
characteristics, together with the fact that this
material is abundant and easily extracted from the
Earth crust, will make SiC devices suitable for
most consumer’s equipment from the Earth crust,
will make SiC devices suitable for most
consumer’s equipment.
9. Conclusion
In conclusion, the impact of wide bandgap
semiconductors on power electronics is a topic of
significant importance in the field of electrical
engineering and semiconductor technology. Over
the past few decades, wide bandgap materials like
silicon carbide (SiC) and gallium nitride (GaN)
have revolutionized power electronics by
offering a range of benefits and presenting a
series of challenges. This technology has the
potential to transform the way we generate,
convert, and manage electrical power.
The challenges associated with the adoption of
wide bandgap semiconductors in power
electronics include initial costs, issues related to
integration, and reliability concerns.
Nevertheless, the opportunities far outweigh
these challenges. Wide bandgap semiconductors
offer higher efficiency, faster switching speeds,
and higher-temperature operation, which can
significantly improve the performance of power
electronic devices. This translates into reduced
energy consumption, increased power density,
and more compact and lightweight power
electronics systems. Additionally, the
introduction of wide bandgap semiconductors
contributes to a more sustainable and eco-friendly
future. By reducing energy losses in power
conversion processes, these materials have the
potential to lower greenhouse gas emissions and
mitigate the impact of climate change. The
impact of wide bandgap semiconductors extends
beyond power electronics and into various sectors
such as renewable energy, electric vehicles, and
aerospace. As these technologies continue to
mature, we can expect greater advancements in
power electronics efficiency and performance.
In conclusion, while challenges remain in terms
of cost, integration, and reliability, the impact of
wide bandgap semiconductors on power
electronics is undeniable. The opportunities for
improved energy efficiency, reduced
environmental impact, and enhanced system
performance make the continued research,
development, and implementation of these
materials a vital priority for the future of power
electronics and sustainable energy systems. As
technology continues to advance, it is likely that
wide bandgap semiconductors will play a central
role in shaping the way we generate and manage
electrical power in the years to come.
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