Introduction
The rapid growth of critical technologies such as 5G telecommunications and electric mobility demandshigher power densities,faster switching frequencies, and greater thermal resilience than is possible with conventional silicon-based semiconductors. As the semiconductor industry explores alternative materials, one promising candidate is gallium nitride (GaN), a compound semiconductor that contains several properties ideally suited for the next generation of high-power, high-frequency electronic systems. With its impressive breakdown field strength,high electron mobility, andwide bandgap, GaN has emerged as a frontrunner in the quest to push the boundaries of electronics, ushering in a new era of energy-efficient and high-performance devices.
The growing adoption of GaN semiconductors is a major opportunity for the United States. It already leads in GaN technology research. With the correct mix of government policy and private initiative in developing and commercializing this new materials technology, the United States could be at the forefront of the next generation of semiconductor innovation. This paper takes a closer look at the rise of gallium nitride devices and the potential for the United States to take a leadership role in this rising segment of the semiconductor industry.
What Is Gallium Nitride?
GaN is a type of semiconductor element known for its wider band gap compared to silicon. This unique characteristic allows GaN to have better efficiency in power conversion compared to conventional silicon semiconductors that are more commonly used today. GaN chips—with their higher speed, lower resistance, lower production cost, and smaller form factor—contribute to less power consumption, a key factor for carbon reduction initiatives, and offer improved performance compared to traditional silicon-based semiconductors.
GaNoffersnumerous advantages, including better durability, the ability to tolerate greater power densities, the ability to operate at higher voltages, and wider operating bandwidth. As a compound semiconductor material with a similar crystal structure to silicon but faster switching speed and higher thermal conductivity, GaNcan outperformsilicon in many applications. GaN is also starting to find use in power electronics like in the automotive industry and data centers, which take advantage of its high voltage and power density. Moreover, GaNplaysan important role in radar systems that are used for foundational national security applications, including autonomous vehicles, radars, and missile defense systems.
The ability to integrate GaN onto silicon substrates opens new possibilities for power-efficient semiconductor devices. Up to this point, commercial GaN products have used sapphire (for light-emitting diodes [LEDs] and laser diodes) and silicon carbide (for radio frequency applications like base stations) substrates. Putting GaN on silicon opens possibilities for power devices and the next generation of LEDs, extremely small LEDs (MicroLEDs).
GaN on silicon for power electronicscan be appliedacross diverse industries, from consumer chargers and power supplies, electric vehicles, and data center power management to military radars and aerospace systems, enabling higher efficiency, smaller form factors, and enhanced capabilities compared to its silicon counterparts.
Both the United States and Chinarecognizethe strategic importance of GaN in maintaining a competitive edge in areas like LEDs, 5G and 6G infrastructure, and defense electronics. With additional GaN markets emerging and poised to grow, protecting related materials and research resources and talents are crucial defense and security concerns.
Why Should the United States Care More about GaN?
U.S. leadership in GaN-based technologies is important to secure technological, commercial, and national security advantages. The U.S. defense industry alreadyreliesheavily on GaN semiconductor technology for advanced radar systems and other applications. GaN is also utilized in 5G and upcoming 6G wireless infrastructure due to its high-frequency performance capabilities. In the optoelectronics domain, GaN-based LEDs have become indispensable for energy-efficient lighting solutions. Furthermore, GaN semiconductors are emerging as a crucial material for power electronics, advances in which are vital to achieving net-zero emissions goals. The ability of GaN-based devices to operate at higher voltages, frequencies, and temperatures makes them essential for electric vehicle power systems, renewable energy infrastructure, and other sustainable innovations driving the transition to agreener industry ecosystem. Securing access to GaN and fostering domestic capabilities in this semiconductor technology is of strategic importance for the United States across national defense and industry frontiers.
It is therefore concerning that Chinese firms like Innoscience, Suzhou Nanowin, HiWafer, and Sanan ICaretoday among the leading GaN technology companies around the world, operating a majority of the GaN fabrication and epitaxy facilities that grow the thin layers of crystals on substrates critical for the production of high-performance and reliable GaN devices. Indeed, China's goal is to become the leader in GaN semiconductors. It is pouring substantial resources into GaN-related research and development, aiming to gain an edge in this critical technology.
Limitations: China’s Role in the GaN Supply Chain
One additional complication pertains to the gallium raw material needed to produce GaN. Currently, China is a primary producer and exporter of both primary and refined gallium, cornering a staggering98 percentof the worldwide primary low-purity gallium production. It is therefore significant that in July 2023, Chinaannouncedrestrictions on critical mineral exports such as gallium and germanium due to national security concerns. These restrictions require special licenses and end user documentation to clear the export of gallium and germanium. This disclosure systemhindersnon-Chinese traders from building buffer stocks, leading to delays. In addition, unclear export approval standards increase uncertainty for the international supply chain and the market.
Since this export control was implemented, China has supposedly notexportedgallium to the United States, heightening the vulnerability of the United States’ gallium supply chain. As a result, therearegrowing concerns about the depletion of gallium stocks in North America—especially for advanced semiconductor chip manufacturing in the U.S. industry. As China starts to weaponize its critical minerals and restricts the rest of the world from accessing necessary resources for advanced technological development, there is a pressing need for the United States to reinforce its gallium supply chain more actively. Accordingly, the United States should also prioritize and strengthen its high-tech research and related policies to successfully lead the next generation of the semiconductor industry.
What Should the United States Do?
To avoid falling behind China in the development of this critical technology, the United States needs to improve several components of its domestic GaN ecosystem. Currently, the United States, along with the United Kingdom and Europe, leads the world in terms of technical capabilities related to GaN semiconductor technology. However, the United States needs to augment its technical lead with investments in the required materials and fabrication infrastructure in order to manufacture GaN materials at scale. In other words, the United States should provide funding that will convert technical expertise into a volume product.
In this regard, the United States and its partners should augment domestic epitaxy capacity. Currently, the United States does not have enough epitaxy capacity, making it reliant on other countries, particularly in East Asia. Securing a domestic epitaxy technology will allow the United States and its allies to participate more robustly in the GaN industry. The United States also should extend its prowess in GaN manufacturing. Failing to increase GaN manufacturing power allows China to leverage the research and development outputs from the United States and its allies, establish manufacturing at scale, and reap the economic benefits of this key technology.
To address this challenge and maintain the United States’ competitive edge, policymakers should explore policies that complement investments in GaN epitaxy technology with the buildout of domestic manufacturing capabilities. TheU.S. CHIPS and Science Actof 2022 increased some industry efforts to bring the silicon carbide semiconductor production plant back to U.S. soil.WolfspeedandBoschhave each announced their plans to invest in and expand their production of silicon carbide chips by 2030. However, despite the CHIPS and Science Act’s intention to bring back chip manufacturing to the United States, the current policy framework does not necessarily focus on securing a supply chain for gallium epitaxy.
Policy Recommendations
U.S. policy efforts to increase the adoption of gallium nitride should focus on three broad areas: (1) increasing U.S. epitaxy capacity, (2) focusing on research and development (R&D) of GaN production technology, and (3) securing gallium supply chains.
- Increasing U.S. epitaxy capacity.
While the U.S. government has increased its investment in GaN fabrication facilities, industry experts have observed that the United States does not have sufficient epitaxy capacity. Consequently, the United States continues to rely on East Asian suppliers, including many in China, to sustain local GaN fabrication facilities. The United States, with its partners, should focus on developing additional capacity in this crucial area to sustain the growing demand for GaN semiconductors. This can be achieved by scaling private epitaxy capacity in the United States. Consideration should be given regarding how an expanded investment tax credit or other mechanisms could incentivize growing the United States’ epitaxy capabilities.
- Funding R&D on GaN production processes.
Another critical bottleneck toward scaling gallium nitride adoption is difficulties in the production process. Gallium nitride on silicon is challenged by inherent lattice mismatch that creates defects degrading the performance of GaN chips. Moreover, it is also difficult toproduceGaN substrates on which GaN crystals can be grown. Together, these issues with GaNmakemass production complicated and expensive compared to silicon. Consideration should be given to how concentrated R&D efforts can gradually overcome these issues.
Currently, U.S. funding for GaN chips is concentrated within the Department of Defense (DOD). Under theTrusted and Assured Microelectronics program, DOD fundingfocuseson the downstream components of GaN supply chains, including expanding fabrication capacity and demonstrating relatively mature GaN-based prototypes. While useful, these projects do not focus on fundamentally improving GaN production processes such as heteroepitaxy.
Consequently, a stronger effort could be directed at basic research aimed at improving the GaN production process within the defense budget. Here, the Defense Advanced Research Projects Agency (DARPA) already has a program of record known asBeyond Scaling Sciencesthat “supports investigations into materials, devices, and architectures to provide continued improvements in electronics performance with or without the benefit of Moore’s Law.” While Beyond Scaling Sciences does have one initiative aimed at improving thermal capacity on existing DOD GaN chips, new independent projects within Beyond Scaling Sciencescould be establishedto further research improving GaN production processes such as epitaxy. Efforts at the DOD level could be further augmented through the efforts of the National Science and Technology Council.
- Securing the gallium supply chain.
To ease China’s control of98 percentof the GaN market, the United States should make efforts toward securing the gallium supply chain. Notably, galliumis nota material that is extant in mineral deposits. Rather, as noted before, it is a byproduct of aluminum production.
While the United States is not a major producer of aluminum, major partner nations including India, Australia, and Canadahavea strong presence in this industry. Indeed, all three nations are members of theMinerals Security Partnership, an initiative that coordinates and develops efforts at shoring up critical mineral production in member nations. The United States can make stronger efforts at friendshoring gallium production in these countries.
Conclusion
GaN’s unique qualities (e.g., higher speed, lower resistance, higher breakdown voltage) make it widely applicable to a diverse set of markets, allowing it to stand apart from silicon-based semiconductors. As such, these abilities underscore its potential to revolutionize strategic industries and bolster national security, especially in defense radar systems and power electronics. Unlike silicon fabs that require costly advanced lithography equipment, GaN production can leverage more cost-effective methods. GaN chipscan be manufacturedon eight-inch wafers using legacy (fully depreciated) equipment. In other words, cutting-edge GaN technology can be produced using fabrication equipment that is obsolete for silicon.
The rapid evolution of critical technologies such as 5G telecommunications and electric mobility necessitates advancements in semiconductor materials, particularly for higher power densities, faster switching frequencies, and greater thermal resilience. As the United States leads in GaN technology research, there exists a significant opportunity for the United States and its allies to lead the charge in the next wave of semiconductor innovation—given the right blend of government policy and private sector initiatives. The geopolitical stakes are higher than ever, and the United States should not pass over the advantages of GaN in its semiconductor strategy.
Sujai Shivakumar is director and senior fellow of the Renewing American Innovation Project at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Julia Yoon is a research intern with the Renewing American Innovation Project at CSIS. Tisyaketu Sirkar is a research intern with the Renewing American Innovation Project at CSIS.
(20min delay)