The Fourth Generation Semiconductor Emerges | Can Gallium Oxide Replace Silicon Carbide?

The Fourth Generation Semiconductor Emerges | Can Gallium Oxide Replace Silicon Carbide?

With the advent of the digital and intelligent era, the semiconductor industry's heat continues to rise. Especially with the rapid development of high-tech fields such as quantum information and artificial intelligence, there has been a push for the rapid update and iteration of semiconductor and multifunctional device technologies. To meet the demands for high performance and low cost, the industry has set its sights on the fourth generation semiconductor, with gallium oxide being the most eye-catching.

With a series of excellent material properties, gallium oxide is expected to change the current landscape of the compound semiconductor market, allowing domestic chip manufacturers to achieve breakthroughs. However, gallium oxide still faces numerous challenges, and this article provides a detailed explanation of its advantages, challenges, and market prospects.

Semiconductor Key Materials Under Export Control

Starting from August 1, 2023, China implemented strict export restrictions on gallium and germanium, key raw materials for semiconductors. Opinions within the industry vary on whether this move is a response to increased export restrictions on photolithography machines by the Dutch company ASML. However, in August 2022, the United States also included a high-purity semiconductor material—gallium oxide—in its export ban on China. The Bureau of Industry and Security (BIS) of the U.S. Department of Commerce announced that fourth-generation semiconductor materials, such as gallium oxide and diamond, resistant to high temperatures and pressures, as well as ECAD software designed for 3nm and below chips, were included in the export control scope.

At that time, not many people paid attention to this, but a year later, China imposed export controls on gallium, prompting the industry to take notice of the critical materials for the fourth generation semiconductor. In the semiconductor industry, gallium and germanium are important raw materials used from the first to the fourth generation of semiconductors. With Moore's Law facing bottlenecks today, semiconductor materials with larger band gaps such as diamond, gallium oxide, AlN, and BN, exhibiting excellent physical properties, have the potential to drive the next generation of information technology.

For China, the development of semiconductor technology has reached a crucial stage, especially with various sanctions imposed by the United States, making breakthroughs in this technology critically important. Despite facing significant challenges, if China can succeed in this semiconductor technology revolution, it has the potential to transform from a "manufacturing powerhouse" to a "manufacturing powerhouse," ushering in the most significant transformation in a century. This is not only a significant test of China's scientific and technological capabilities but also a great opportunity to showcase China's response to global scientific and technological challenges.

Surpassing Silicon Carbide: Advantages of Gallium Oxide

Gallium oxide, a fourth-generation semiconductor material, has advantages such as a large bandgap (4.8 eV), high critical breakdown field (8 MV/cm), and good conductivity. Gallium oxide has five confirmed crystal forms, with β-Ga2O3 being the most stable. Its bandgap is 4.8–4.9 eV, and the critical breakdown field reaches 8 MV/cm. Its conductivity is much lower than SiC and GaN, significantly reducing device conduction losses. Its specific figure of merit (BFOM) is as high as 3400, approximately 10 times that of SiC and four times that of GaN.

Graph: Semiconductor materials sorted by bandgap width

Compared to silicon carbide and gallium nitride, the growth process of gallium oxide can use a liquid melt method under atmospheric pressure, resulting in high quality, large production yields, and low costs. However, materials like SiC and GaN can currently only be prepared using a vapor-phase method, requiring higher temperatures and energy consumption. This means that in production, gallium oxide may have a cost advantage, and domestic factories are likely to quickly expand production capacity.

Graph: Properties of fourth-generation semiconductors

Compared to SiC, gallium oxide excels in all aspects. Its larger bandgap width and higher critical breakdown field, especially, give it a significant advantage in high-power and high-frequency applications.

Specific Applications and Market Potential of Gallium Oxide

The development prospects of gallium oxide are becoming increasingly prominent, with the current market mainly monopolized by two giants, Novel Crystal Technology (NCT) and Flosfia, both based in Japan. NCT started researching gallium oxide in 2012, successfully breaking through key technologies, including 2-inch gallium oxide crystals and epitaxy technology, as well as mass production of gallium oxide materials. Its efficiency and high performance have been widely recognized in the industry. In 2021, it successfully mass-produced 4-inch gallium oxide wafers and began supplying them to customers, maintaining Japan's leading position in the competition for third-generation compound semiconductors.

According to NCT's predictions, the market for gallium oxide wafers will experience significant growth in the next decade, expanding to approximately RMB 3.02 billion by 2030. FLOSFIA predicts that by 2025, the market size of gallium oxide power devices will begin to surpass gallium nitride, reaching USD 1.542 billion (about RMB 10 billion) by 2030, accounting for 40% of silicon carbide and 1.56 times that of gallium nitride. According to Fuji Economics' forecast, by 2030, the market size of gallium oxide power devices will reach JPY 154.2 billion (about RMB 9.276 billion), surpassing the market size of gallium nitride power devices. This trend reflects the importance of gallium oxide in power electronic devices and its future potential.

Global power device market and gallium oxide power device market size (million USD), source: FLOSFIA

In specific application areas, gallium oxide has significant advantages. In the field of power electronics, gallium oxide power devices partially overlap with gallium nitride and silicon carbide. In the military domain, they are mainly used in high-power electromagnetic guns, power control systems for tanks, fighter jets, and ships, as well as radiation-resistant and high-temperature aerospace power sources. In the civilian sector, they are primarily applied in areas such as the power grid, electric power traction, photovoltaics, electric vehicles, household appliances, medical devices, and consumer electronics.

Graph: FLOSFIA's market strategy for gallium oxide power devices, source: FLOSFIA

The market for gallium oxide has also found significant opportunities in the new energy vehicle sector. However, domestically, the field of power devices for vehicle regulations has been weak, with no SiC MOS IDM meeting vehicle regulations. Although some fabless companies in XFab can quickly develop comprehensive SBD and MOS specifications for the market and have made smooth progress in sales and financing, the future still requires the construction of FAB for IDM to master capacity and develop proprietary processes for differentiated competitive advantages.

Charging stations are very cost-sensitive, providing an opportunity for gallium oxide. If it can meet or even exceed performance requirements while gaining market acceptance with cost advantages, gallium oxide has great potential for application in this field.

In the RF device market, the market potential of gallium oxide can be compared to that of silicon carbide epitaxial gallium nitride devices. The core of new energy vehicles is the inverter, which demands very high specifications for devices. Currently, companies like Infineon, Hitachi, ON Semiconductor, and Rohm can mass-produce and supply automotive-grade SiC MOSFETs. It is projected that by 2026, this figure will grow to $2.22 billion (approximately RMB 15 billion), indicating that gallium oxide has broad application prospects and market potential in the RF device market.

Another crucial application in the field of power electronics is the 48V battery. With the widespread use of lithium-ion batteries, higher voltage systems can replace the 12V voltage systems of lead-acid batteries, achieving efficiency, weight reduction, and energy-saving goals. These lithium-ion battery systems will widely adopt a 48V voltage, requiring efficient 48V→12V/5V conversion for electronic power systems. Taking the two-wheeled electric vehicle market as an example, according to data from 2020, the overall production of electric two-wheelers in China was 48.34 million units, a year-on-year growth of 27.2%, with a lithium-ion penetration rate exceeding 16%. Facing such a market, 100V-rated high-current devices like gallium oxide, GaN, and silicon-based SG-MOS are targeting this application.

In the industrial sector, gallium oxide presents several opportunities and advantages, including unipolar substitution for bipolar, higher energy efficiency, ease of large-scale production, and a demand for reliability. These characteristics suggest that gallium oxide may play a significant role in future power applications. In the long term, gallium oxide power devices are expected to play a role in the 650V/1200V/1700V/3300V market and are expected to fully penetrate the automotive and electrical equipment sectors from 2025 to 2030. In the short term, gallium oxide power devices will first appear in consumer electronics, household appliances, and high-reliability, high-performance industrial power supplies. Its features may create competition among materials such as silicon (Si), silicon carbide (SiC), and gallium nitride (GaN).

The author believes that in the next few years, the focus of competition for gallium oxide will be in the 400V platform, specifically in the conventional use of 650V devices. Competition in this field will involve factors such as switch frequency, energy loss, chip cost, system cost, and reliability. However, with technological advances, the platform may upgrade to 800V, requiring the use of 1200V or 1700V devices, which are already advantageous areas for SiC and Ga2O3. In this competition, startups have the opportunity to establish a solid foundation for inverter applications with automotive customers by engaging in deep communication, building scenario awareness, adhering to vehicle regulations, and understanding customer preferences.

In conclusion, gallium oxide has significant potential in the power device field, competing with materials like SiC and GaN in various sectors to meet the requirements of high-efficiency, low energy consumption, high frequency, and high-temperature applications. However, the penetration of new materials in applications such as inverters and chargers requires time, continuous development of specifications tailored to specific applications, and gradual market expansion.

Applications of Gallium Oxide