Have you heard of "Gallium Nitride" (GaN)? Compared to the silicon you and I are familiar with, this compound semiconductor is more resistant to high voltage, high temperature, and high current, making it suitable for the high-frequency and lightweight electronic product market. In the fields of 5G/6G mobile communications, drones, self-driving cars, radar, etc., GaN has great potential. Therefore, it has become a popular option for research in various fields in the past decade, and Taiwan is of course no exception. Zhang Yi, Dean of the School of International Semiconductor Industry at National Yang Ming Chiao Tung University, is dedicated to the research of GaN components and processes. In order to achieve breakthroughs in Taiwan's system integration and technology, he found the "strongest comrades" through journal articles and started a multi-year collaboration with a German team...
"Adding friends" through journal articles marks the beginning of cross-border cooperation
Dean Chang Yi has dedicated over 30 years to the study of semiconductor materials and is a pioneer in Taiwan's compound semiconductor industry. Gallium nitride research has recently become a key focus. Early on, he achieved the world's highest frequency of 780 GHz using gallium arsenide. Following the rise of gallium nitride, which has become the most important semiconductor after silicon, he has continued to advance research in this field.
Speaking of the collaboration with Germany, Dean Chang Yi recalled, "I discovered from a journal article that the Ferdinand-Braun-Institut (FBH) in Germany not only had a solid foundation in high-frequency IC (integrated circuit) design, but also extensive experience in packaging. Given the relative lack of talent and resources in this field in Taiwan at the time, I volunteered to write to them, saying I wanted to visit them in Berlin. I was taking my doctoral students to Munich, Germany, for the European Microwave Conference. They graciously welcomed us." Packaging is a crucial component in semiconductor design and manufacturing. From a macro perspective, it impacts power consumption, performance, and cost, while at a micro level, it influences the fundamental functionality of the chip. Think of the package as the "container" for the semiconductor chip. Considerations include protecting the chip, connecting it to the circuit board, and ensuring high-frequency functionality and heat dissipation.
This decision launched a multi-year journey of international collaboration for President Chang. He believed that Taiwan could leverage its advantages in semiconductor device manufacturing processes to gain access to FBH's expertise in high-frequency packaging and design, thereby benefiting system integration. He also noted the close collaboration within the European Union, with research projects often jointly undertaken by institutions in different countries. This provided Taiwan with access to a wider range of technological resources.
Silicon and gallium arsenide, out! This is the era of gallium nitride.
Many people may not be familiar with gallium nitride, an important third-generation semiconductor[1] material. Dean Zhang Yi explained that it has characteristics such as a wide band gap, high electron mobility (the speed at which electrons move through a metal or semiconductor under the pull of an electric field), and high breakdown voltage (the maximum voltage that can be applied to a material before it becomes conductive). "I realized very early on that the US military had begun to transfer all its gallium arsenide development to gallium nitride, so I quickly invested in this field."
Professor Zhang Yi and his research team recently used metal-organic chemical vapor deposition (MOCVD) to grow gallium nitride single crystals on silicon or silicon carbide substrates (a technique known as epitaxy). They also introduced a "quantum well" into the gallium nitride material. This unique structure features high sides and a low center, with the sides and center composed of different semiconductors with different energy band gaps. Because the electrons conducted in the center are relatively low in energy, they are confined to this region, allowing for high-speed transmission without collisions with other ions, thereby improving device performance. "Unlike previous silicon, gallium nitride has numerous energy levels on its surface that can spontaneously release electrons, eliminating the need for dopants. Generally, semiconductors require dopants to conduct current, but this material does not. Instead, it generates a high current by naturally supplying electrons through dangling bonds (unsatisfied atomic valences that can react with foreign ions or molecules by sharing electron pairs) on the semiconductor's surface," Professor Zhang explained in detail the unique features of this material.
From military to life, allowing signals to travel farther and more instantly
Gallium nitride (GaN) technology initially gained attention in the military due to the increasing demands placed on communication systems in modern warfare. For example, radars needed to be smaller, with improved lock range and resolution to enhance flight performance. Thanks to GaN's high power density (the amount of power it can handle within a given space), radar systems could be reduced in size. This performance allowed drones to significantly extend their communication range while reducing their payload size, opening up new possibilities for the advancement of intelligent combat equipment.
Gallium nitride benefits not only the military but also civilian sectors, playing a key role in the development of communications infrastructure. Gallium nitride radio frequency (RF) components are crucial for achieving high-speed, high-data-volume, and low-latency communications. "For example, when watching Olympic Channel games, how can we instantly and clearly transmit those images to the stadium's big screen? Gallium nitride is crucial here." Dean Zhang Yi also mentioned the recent popularity of self-driving cars: "Self-driving cars require wireless communication transceiver systems that can quickly transmit large amounts of data. Cars cannot rely solely on their own data processing. Imagine a self-driving car is running, it needs to collect a large amount of surrounding data and quickly transmit it to the car for processing, so that it can quickly determine when to turn or what to do. If the data volume is not large enough or the speed is not fast enough, the car may collide or fail to make a turn in time." These examples show that gallium nitride is about to become an everyday part of our lives.
A new generation of energy saving masters, saving the electricity of a nuclear power plant
In addition to high frequencies, gallium nitride also has significant power-saving applications, such as in RF power amplifiers. An RF power amplifier is an electronic device that converts low-power RF signals into high-power signals. It boosts weak radio signals to a level sufficient for long-distance transmission, ensuring strong and distortion-free signals (more precisely, this requires not only a lack of noise but also consistent signal input and output). This allows devices to operate over a wide frequency range, benefiting radio broadcasting, mobile communications, radar systems, medical equipment, and even household appliances like microwave ovens.
GaN also plays a role in Taiwan's active interaction with AI computing company NVIDIA. President Chang Yi noted, "When AI is combined with semiconductors, it requires a lot of computing. However, AI is very power-hungry; even when it's not being used, it continues to compute. If data centers adopted materials like GaN, a single data center could save the same amount of electricity as an entire nuclear power plant." However, Chang also noted that this problem hasn't yet occurred simply because AI data centers currently don't use that much electricity. "If there were a lot of data centers, the government would need to implement policies telling everyone: 'You must do this (to save energy), or we won't let you operate,' because excessive power consumption would have a significant impact on the environment."
Professor Chang Yi used the example of a mobile phone: "Nowadays, iPhones don't come with chargers, and if the charger's current efficiency isn't high enough, it won't charge. This presents a great opportunity for gallium nitride, which can be more energy-efficient." For telecommunications service providers, using substandard transistors and ICs can lead to excessive noise, resulting in high power consumption and ultimately disrupting the entire system. "If these telecommunications companies implement regulations requiring power-saving devices, good communication quality, and low noise, then gallium nitride will have a huge future," Professor Chang Yi said.
Pre-ordering the future: How is Taiwan making a name for itself in the field of gallium nitride?
Next, breakthroughs in manufacturing process technology will be crucial for the large-scale adoption of GaN technology. President Zhang Yi emphasized that if the government can formulate relevant industrial policies, such as encouraging the adoption of high-efficiency GaN-based power supplies from the perspective of energy conservation and carbon reduction, this will likely accelerate industrialization.
He also reiterated the importance of gallium nitride to communication systems: "Communication systems must meet the needs of future applications, and how they are integrated with components requires consideration. How can these components send signals? How can they avoid interference? How can the signals be relatively simple and noise-free? How can they accommodate more signals? These are all closely related to the overall design and production of the components." Dean Zhang Yi pointed out that if we have a good theoretical foundation in these areas, we will have the opportunity to do better than those abroad.
Furthermore, we must further connect domestic and international industry, academia, and research resources, strengthening our comprehensive approach from materials and components to modules and systems to gain an advantage. "In Taiwan, semiconductors are our strength, and building an entire industry chain is possible." Currently, Dean Chang Yi's team has collaborated with several top international universities, such as Nagoya University in Japan on high-frequency, high-power transistors, and the University of California, Los Angeles (UCLA) in the United States on high-frequency circuit design.
"Every country has different expertise, and every university has limited resources. We may be able to excel in one area, but when it comes to the entire system, including packaging, crystal growth, and IC design, the costs are considerable. This is when we need to collaborate with others and integrate their existing expertise with our research." Dean Chang Yi's actions effectively integrate the advantages of various resources, accelerate innovative breakthroughs in core technologies, and enhance Taiwan's international influence in the field of gallium nitride.
Combining advantages such as lightweight, high-voltage resistance, power efficiency, and high-speed data transmission, gallium nitride is rapidly infiltrating our lives and even playing a key role in next-generation communications. We look forward to scientists continuing to achieve breakthroughs in RF, transistor, and circuit design, thereby creating new technologies with even greater efficiency and energy savings!
Notes
[1] The first generation is silicon and germanium, the second generation is gallium arsenide (GaAs) and indium phosphide (InP), and the third generation is silicon carbide (SiC) and gallium nitride.
Source: Interview with Zhang Yi, Dean of the International Semiconductor Industry College at National Yang Ming Chiao Tung University
This article is reprinted from Science and Technology Grand View Garden. The original title is "From military applications to improving AI computing energy consumption, see how the compound semiconductor "Gallium Nitride" opens the door to next-generation communications and applications!"
Sources:Environmental Information Center
