In today’s society, using electric power as efficiently as possible has become a major theme.

In fields dealing with high voltage and high current — electric vehicles (EVs), renewable energy, and industrial equipment — silicon (Si) is approaching the limits of its performance.

 

This is where wide-bandgap (WBG) semiconductors come in. Materials such as SiC (silicon carbide), GaN (gallium nitride), and Ga₂O₃ (gallium oxide) are the leading examples, and they are drawing significant attention as the next generation of power semiconductor materials.

A power semiconductor is a device used to control, convert, and supply electricity. It is primarily used in inverters and converters to switch electrical power, handling tasks such as driving motors, converting power, and controlling charging.

 

In essence, it acts as an electrical valve that determines energy efficiency — and improving this performance is a key part of achieving a decarbonized society.

Characteristics

・A compound of silicon and carbon.

・Band gap: approximately 3.2 eV (about three times that of silicon).

・Dielectric breakdown field: approximately 10 times that of silicon.

・Thermal conductivity: approximately 3 times that of silicon.

Strengths

・Strong resistance to high voltage (1,200V and above) and high-temperature operation (up to around 600°C class).

・Low switching losses, delivering significant energy savings.

・High heat dissipation, helping enable smaller device packaging.

Main applications

・Inverters for EVs and hybrid vehicles

・Inverters for industrial equipment, railways, and solar power generation

・Power conversion equipment for high-temperature environments

Challenges

・Crystal defects occur relatively easily, driving up wafer manufacturing costs.

・Processing is difficult, resulting in lower yields.

Even so, demand for SiC is surging as a material that supports the “heart” of EVs.

Characteristics

・Band gap: approximately 3.4 eV (wider than silicon’s).

・High electron mobility, giving it excellent high-frequency performance.

・A direct-gap material with strong optical response (it is also used as an LED and laser material).

Strengths

・High-speed switching significantly reduces switching losses.

・Enables compact, lightweight power supply designs.

・Well suited to 5G communications, power conversion, and wireless power transfer.

Main applications>

・Fast chargers for smartphones (GaN chargers)

・Server power supplies and data center energy efficiency

・5G and millimeter-wave amplifiers, radar, and satellite communication equipment

Challenges

・Reliability at high voltages (above 1,200V) still lags behind SiC.

・Substrate costs (primarily sapphire and SiC substrates) and heat dissipation remain challenges.

Even so, GaN remains a leading candidate for achieving the combination of high frequency, high efficiency, and miniaturization.

Characteristics

・Band gap: approximately 4.9 eV — among the widest of any WBG material.

・Dielectric breakdown field roughly 8 to 10 times that of silicon.

・Theoretically capable of even higher voltage tolerance than SiC or GaN.

Strengths

・Capable of supporting devices with extremely high voltage tolerance (10kV and above).

・Large-area substrates can be manufactured inexpensively via solution growth.

・Expected to become a next-generation material for ultra-high-voltage power conversion devices.

Challenges

・Low thermal conductivity makes heat-dissipation design difficult.

・Low electron mobility makes it poorly suited to high-speed operation.

・Crystal growth technology is still developing, and mass production remains a future goal.

Ga₂O₃ is drawing worldwide attention as a potential “post-SiC” material, even as it remains largely at the research stage.

・Si: Mature, inexpensive, low voltage tolerance (suited to existing equipment)

・SiC: High voltage tolerance, high temperature, leading choice for EVs (energy-efficiency focused)

・GaN: High speed, high frequency, compact (suited to communications and charging)

・Ga₂O₃: Ultra-high voltage tolerance, potential for low cost (still at the research stage)

The industry is moving toward an era in which each material’s strengths are leveraged for the applications best suited to it.

・Material designs that combine high voltage tolerance, high-temperature operation, and high efficiency.

・Growing importance of heat dissipation, sealing, and packaging technologies.

・Hybridization with silicon technology (such as Si-based GaN and SiC MOSFETs).

・Compliance with reliability testing and automotive-grade quality standards (such as AEC-Q101).

Increasingly, competitiveness comes not from the material itself, but from system-level optimization.

・A 5–10% improvement in power conversion efficiency per EV could extend driving range by roughly 10%.

・These materials also contribute to energy savings at power plants and data centers, delivering substantial CO₂ reduction.

・Next-generation semiconductors are becoming a cornerstone of green technology.

Technological innovation in this area translates directly into improvements in the planet’s overall energy efficiency.

・Optimizing crystal defects, thermal design, and cost.

・Standardizing mass production and reliability evaluation.

・Achieving optimal system design by using each material where it’s best suited.

・Leveraging AI for materials design and process optimization.

Over the next decade, a shift from Si to SiC/GaN and eventually to Ga₂O₃ is likely to continue advancing.

・SiC, GaN, and Ga₂O₃ are next-generation power semiconductor materials that go beyond the limits of silicon.

・Each has its own strengths and challenges, requiring the optimal choice to be made based on application.

・These materials form a core technology supporting energy efficiency in EVs, renewable energy, communications, and other social infrastructure.

・They are the leading materials for an era defined by devices that operate smaller, faster, and hotter than ever before.

1.What do SiC, GaN, and Ga₂O₃ have in common?

2.What is the main difference between SiC and GaN?

3.Why is Ga₂O₃ drawing attention?

 

 

Column Supervisor: Koji Kakumoto (Otis Group Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined Otis Group Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as Representative Director, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.