Researchers at Texas State University have pioneered a novel manufacturing technology that could lower the cost and improve the performance of radio frequency (RF) semiconductors used in wireless cellular networks and radar systems. Their breakthrough tackles a longstanding weakness in gallium nitride (GaN)-on-silicon semiconductors, the chips that amplify and transmit high-frequency signals in wireless networks.
For years, silicon's performance limitations have stood in the way of making high-performance gallium nitride semiconductors more affordable. Now, researchers at TXST’s Center for Research, Entrepreneurship and Science and Technology (CREST), led by Edwin L. Piner, Ph.D., professor and CREST director, in collaboration with Atomera Incorporated, have addressed that challenge and paved the way for lower-cost, more energy-efficient semiconductor components with improved performance.
“GaN-on-silicon has historically limited RF performance in terms of both radio frequency and device efficiency,” Piner said. “The Texas State-Atomera collaboration has addressed this limitation, thereby enabling devices that use less energy and are capable of being developed for advanced market applications.”
GaN-based semiconductors are commonly used in technologies such as wireless communication networks, satellite systems, radar platforms, and other high-frequency electronics because of their ability to operate at high frequencies and power levels. While devices built on silicon carbide substrates offer excellent performance, their high manufacturing costs have limited widespread adoption. Silicon substrates provide a lower-cost alternative, but unwanted electrical effects have traditionally prevented them from matching the performance of their silicon carbide counterparts.
To solve the problem, the researchers tested Atomera's Mears Silicon Technology (MST), a manufacturing process that adds a thin, oxygen-rich layer inside the silicon wafer. This layer acts as a barrier, stopping gallium and aluminum atoms from drifting into the silicon as the semiconductor is built. Without the barrier, the stray atoms can create an unwanted path for electrical current and cause signal loss, distortion, and lower efficiency in high-frequency devices.
Piner and his team, consisting of Jonathan W. Anderson, Ph.D., Daniel Bailey, and Ganesh Aryal (both students in the Materials Science, Engineering, and Commercialization doctoral program) grew and tested semiconductor structures made both with and without the MST diffusion barrier. Their results showed that MST reduced interfacial charge—unwanted electrical charge that builds up where different materials meet—over tenfold compared with conventional GaN-on-silicon structures. The researchers also found that far fewer impurities migrated into the silicon substrate, helping prevent the formation of a parasitic channel, an unwanted pathway that can interfere with device performance.
The improvement has significant implications for RF performance. By reducing parasitic charge and related losses, the technology gives low-cost GaN-on-silicon devices much higher linearity than has typically been possible. Improved linearity can lead to better signal quality and more efficiency in communications and sensing systems.
Thanks to the research team, GaN-on-silicon devices could perform almost as well as more expensive semiconductor technologies while keeping silicon's cost and manufacturing advantages.
“Dr. Piner’s team has developed a world-class RF GaN-on-Si baseline, making them an ideal collaborator to evaluate the impact of our MST technology," said Robert Mears, Ph.D., founder and chief technology officer at Atomera. "By combining TXST’s baseline GaN stack on our MST silicon wafers, we have been able to demonstrate the low RF losses, high linearity and ultra-low crosstalk performance characteristics that RF designers are looking for in developing next-generation wireless networks."
The innovation also highlights TXST's growing leadership in advanced semiconductor materials and devices. The research addresses critical technological barriers in communications and defense technologies and demonstrates strong commercialization potential in the rapidly expanding semiconductor market.
“GaN devices are widely used in cellular networks, satellite communications, and defense radar systems,” Piner said. “In military missile tracking systems, performance improvements can translate into systems that are 10 times more effective in defensive capabilities.”
This breakthrough builds on CREST's efforts to advance gallium nitride semiconductor technology for high-frequency, high-power electronic applications. Piner, a pioneer among those who helped develop GaN-on-silicon technology in the early 2000s, has continued to advance the field since joining TXST in 2010.
“The Texas State-Atomera team plans to continue improving the technology's performance while ensuring the process is consistent and repeatable,” Piner said. “Our goal is to help accelerate its path to commercial adoption.”
About Atomera
Atomera Incorporated is a semiconductor materials and technology licensing company focused on deploying its proprietary performance-enhancing technology into the semiconductor industry. Atomera has developed Mears Silicon Technology™, or MST®, a quantum-engineered thin-film technology that increases performance and power efficiency in semiconductor transistors. MST can be implemented using equipment already deployed in semiconductor manufacturing facilities and is complementary to other nano-scaling technologies in the semiconductor industry roadmap. Explore our GaN-on-silicon white paper for details. More information can be found at www.atomera.com.