Exploring the Future Prospects of Silicon Semiconductor Chips

What defines the role of semiconductors in technology?

Materials can be classified based on their electrical conductivity—current flows easily in conductors but cannot in insulators. Semiconductors fall in between: they can conduct electricity under specific conditions, making them extremely useful in computing. By utilizing semiconductors as the foundation for microchips, we can control the flow of electricity within devices, enabling all the remarkable functions we rely on today.

Since their inception, silicon has dominated the chip and technology industry, leading to the term “Silicon Valley.” However, it may not be the most suitable material for future technologies. To understand this, we must revisit how chips function, the current technological challenges, and the materials that may replace silicon in the future.

How do microchips translate inputs into computer language?

Microchips are filled with tiny switches called transistors, which translate keyboard inputs and software programs into computer language—binary code. When a switch is open, current can flow, representing a '1’; when closed, it cannot, representing a '0’. Everything modern computers do ultimately boils down to these switches.

For decades, we’ve improved computing power by increasing the density of transistors on microchips. While the first microchip contained just one transistor, today we can encapsulate billions of these tiny switches in chips the size of a fingernail.

The first microchip was made of germanium, but the technology industry quickly realized that silicon was a superior material for chip manufacturing. Silicon’s primary advantages include its abundance, low cost, and higher melting point, which means it performs better at elevated temperatures. Additionally, silicon is easy to “doped” with other materials, allowing engineers to adjust its conductivity in various ways.

What challenges does silicon face in modern computing?

The classic strategy of creating faster, more powerful computers by continually shrinking the transistors in silicon chips is beginning to falter. Deep Jariwala, a professor of engineering at the University of Pennsylvania, stated in a 2022 interview with The Wall Street Journal, “While silicon can work at such small dimensions, the energy efficiency required for a computation has been rising, making it extremely unsustainable. From an energy standpoint, it no longer makes sense.”

To continue improving our technology without further harming the environment, we must address this sustainability issue. In this pursuit, some researchers are closely examining chips made from semiconductor materials other than silicon, including gallium nitride (GaN), a compound made from gallium and nitrogen.

Why is gallium nitride gaining attention as a semiconductor material?

The electrical conductivity of semiconductors varies, primarily due to what is known as the “bandgap.” Protons and neutrons cluster in the nucleus, while electrons orbit around it. For a material to conduct electricity, electrons must be able to jump from the “valence band” to the “conduction band.” The minimum energy required for this transition defines the material’s bandgap.

In conductors, these two regions overlap, resulting in no bandgap—electrons can pass freely through these materials. In insulators, the bandgap is very large, making it difficult for electrons to traverse even with significant energy applied. Semiconductors, like silicon, occupy a middle ground; silicon has a bandgap of 1.12 electron volts (eV), while gallium nitride boasts a bandgap of 3.4 eV, categorizing it as a “wide bandgap semiconductor” (WBGS).

WBGS materials are closer to insulators in the conductivity spectrum, requiring more energy for electrons to move between the two bands, making them unsuitable for very low-voltage applications. However, WBGS can operate at higher voltages, temperatures, and energy frequencies than silicon-based semiconductors, allowing devices that utilize them to run faster and more efficiently.

Rachel Oliver, director of the Cambridge GaN Centre, told Freethink, “If you put your hand on a phone charger, it will feel hot; that’s the energy wasted by silicon chips. GaN chargers feel much cooler to the touch—there’s significantly less wasted energy.”

Gallium and its compounds have been utilized in the tech industry for decades, including in light-emitting diodes, lasers, military radar, satellites, and solar cells. However, gallium nitride is currently the focus of researchers who hope to make technology more powerful and energy-efficient.

What implications does gallium nitride hold for the future?

As Oliver mentioned, GaN phone chargers are already on the market, and researchers aim to leverage this material to develop faster electric vehicle chargers, addressing a significant consumer concern regarding electric vehicles. “Devices like electric vehicles can charge much more quickly,” Oliver said. “For anything that requires portable power and rapid charging, gallium nitride has significant potential.”

Gallium nitride can also enhance the radar systems of military aircraft and drones, allowing them to identify targets and threats from greater distances, and improve the efficiency of data center servers, which is crucial for making the AI revolution affordable and sustainable.

Given that gallium nitride excels in many aspects and has been around for some time, why does the microchip industry continue to build around silicon? The answer, as always, lies in cost: GaN chips are more expensive and complex to manufacture. Reducing costs and scaling production will take time, but the U.S. government is actively working to kickstart this emerging industry.

In February 2024, the United States allocated $1.5 billion to semiconductor manufacturing company GlobalFoundries under the CHIPS and Science Act to expand domestic chip production.

 A portion of these funds will be used to upgrade a manufacturing facility in Vermont, enabling it to mass-produce gallium nitride (GaN) semiconductors, a capability that is currently not realized in the U.S. According to the funding announcement, these semiconductors will be utilized in electric vehicles, data centers, smartphones, power grids, and other technologies. 

However, even if the U.S. manages to restore normal operations across its manufacturing sector, the production of GaN chips is contingent upon a stable supply of gallium, which is currently not guaranteed. 

While gallium is not rare—it is present in the Earth’s crust at levels comparable to copper—it does not exist in large, mineable deposits like copper. Nonetheless, trace amounts of gallium can be found in ores containing aluminum and zinc, allowing for its collection during the processing of these elements. 

As of 2022, approximately 90% of the world’s gallium was produced in China. Meanwhile, the U.S. has not produced gallium since the 1980s, with 53% of its gallium imported from China and the remainder sourced from other countries. 

In July 2023, China announced it would begin restricting exports of gallium and another material, germanium, for national security reasons. 

China’s regulations do not outright ban gallium exports to the U.S., but they require potential buyers to apply for permits and obtain approval from the Chinese government. 

U.S. defense contractors are almost certain to face rejections, especially if they are listed on China’s “unreliable entity list.” So far, these restrictions appear to have resulted in increased gallium prices and extended order delivery times for most chip manufacturers, rather than an outright shortage, although China may choose to tighten its control over this material in the future. 

The U.S. has long recognized the risks associated with its heavy reliance on China for critical minerals—during a dispute with Japan in 2010, China temporarily banned the export of rare earth metals. By the time China announced its restrictions in 2023, the U.S. was already exploring methods to strengthen its supply chains. 

Possible alternatives include importing gallium from other countries, such as Canada (if they can sufficiently ramp up production), and recycling the material from electronic waste—research in this area is being funded by the U.S. Department of Defense’s Advanced Research Projects Agency. 

Establishing a domestic supply of gallium is also an option. 

Nyrstar, a company based in the Netherlands, indicated that its zinc plant in Tennessee could extract enough gallium to meet 80% of current U.S. demand, but constructing the processing facility would cost up to $190 million. The company is currently negotiating with the U.S. government for expansion funding.

Potential gallium sources also include a deposit in Round Top, Texas. In 2021, the U.S. Geological Survey estimated that this deposit contains approximately 36,500 tons of gallium—by comparison, China produced 750 tons of gallium in 2022. 

Typically, gallium occurs in trace amounts and is extremely dispersed; however, in March 2024, American Critical Materials Corp. discovered a deposit with a relatively high concentration of high-quality gallium in the Kootenai National Forest in Montana. 

Currently, gallium from Texas and Montana has yet to be extracted, but researchers from Idaho National Laboratory and American Critical Materials Corp. are collaborating to develop an environmentally friendly method for obtaining this material. 

Gallium is not the only option for the U.S. to improve microchip technology—China can produce more advanced chips using some unconstrained materials, which in some cases may outperform gallium-based chips. 

In October 2024, chip manufacturer Wolfspeed secured up to $750 million in funding through the CHIPS Act to build the largest silicon carbide (also known as SiC) chip manufacturing facility in the U.S. This type of chip is more expensive than gallium nitride but is preferable for certain applications, such as high-power solar power plants. 

Oliver told Freethink, “Gallium nitride performs very well at certain voltage ranges, while silicon carbide performs better at others. So it depends on the voltage and power you are dealing with.” 

The U.S. is also funding research into microchips based on wide-bandgap semiconductors, which have a bandgap greater than 3.4 eV. These materials include diamond, aluminum nitride, and boron nitride; although they are costly and challenging to process, chips made from these materials may one day offer remarkable new functionalities at lower environmental costs.

 “If you’re talking about the types of voltages that might be involved in transmitting offshore wind power to the onshore grid, gallium nitride may not be suitable, as it cannot handle that voltage,” Oliver explained. “Materials like aluminum nitride, which are wide-bandgap, can.”