NTT Unveils World's First AlN-Based High-Frequency Transistor, Paving Way for Post-5G Era

NTT has successfully developed and operated the world's first aluminum nitride (AlN)-based high-frequency transistor, a significant leap forward for advanced wireless communication. This groundbreaking achievement was announced by the company on December 9, 2025.

The innovation expands the potential applications of AlN, a material previously recognized primarily for power conversion, into the realm of cutting-edge wireless communication systems. This includes technologies designed for the post-5G era and beyond.

This breakthrough leverages AlN's superior intrinsic properties, which are ideal for handling both high power and high frequencies, crucial requirements for next-generation wireless networks. The material's characteristics enable more efficient and robust signal processing.

According to NTT, the newly developed transistors are capable of amplification in the millimeter-wave band, a critical frequency range for high-speed data transmission. This performance marks a new benchmark for AlN-based devices.

The research findings will be formally presented at the prestigious 71st IEEE International Electron Devices Meeting (IEDM 2025) in San Francisco today, December 10, 2025. This presentation will detail the technical advancements.

This development is expected to significantly enhance wireless communication services, offering expanded coverage areas and substantially faster communication speeds. Such improvements are vital for the evolving demands of the post-5G landscape.

NTT's success addresses long-standing technical hurdles, including high contact resistance and channel resistance, which previously limited AlN's high-frequency signal amplification capabilities. The company engineered specific design solutions to overcome these challenges.

• Background and Material Advantages: Aluminum nitride (AlN) is an ultra-wide bandgap semiconductor known for its exceptional thermal conductivity, electrical insulation, and ability to withstand high electric fields. According to everything RF in October 2024, these properties make it highly attractive for high-power and high-frequency electronic devices. While traditional 5G systems often rely on gallium nitride (GaN) transistors, AlN offers an even larger breakdown electric field and superior heat dissipation, making it a prime candidate for future communication needs.

• Overcoming Technical Hurdles: A key aspect of NTT's achievement was successfully addressing the inherent challenges in AlN-based transistors, specifically high contact resistance and high channel resistance. NTT's press release on December 9, 2025, detailed that researchers designed a novel contact layer to reduce the energy barrier at the electrode-semiconductor interface and optimized the channel structure to achieve a high electron concentration. This intricate engineering allowed for efficient high-frequency signal amplification, which was previously a significant barrier.

• Implications for Post-5G and 6G Communications: This breakthrough is a crucial enabler for the next generation of wireless communication, often referred to as post-5G or 6G. As reported by microspace Communications in September 2024, 6G is projected to offer speeds exceeding 100 Gbps and significantly lower latencies than 5G, requiring components capable of operating at much higher frequencies, potentially into the terahertz spectrum. The AlN-based transistor's ability to amplify millimeter-wave signals efficiently directly supports these future requirements, promising enhanced data rates and expanded network capacity.

• NTT's Legacy in AlN Development: NTT has a long history of pioneering work with aluminum nitride. The company was the first in the world to successfully convert AlN into a semiconductor in 2002, opening new avenues for its application. Science Japan reported in June 2022 that NTT further demonstrated the operation of AlN transistors for power devices, showcasing its potential for ultra-low loss power conversion. This latest development extends NTT's leadership in AlN technology from power electronics to high-frequency wireless communications.

• Competitive Landscape and Related Research: While NTT has achieved the world's first AlN-based high-frequency transistor, other institutions are also exploring AlN's potential. Cornell University engineers, for instance, developed an AlN-based XHEMT transistor for RF power amplifiers, emphasizing its benefits for 5G and emerging 6G networks due to superior thermal management and defect reduction, as Electronics For You reported in December 2025. This indicates a broader industry recognition of AlN as a critical material for future high-performance electronics.

• Future Outlook and Practical Applications: The successful operation of AlN-based high-frequency transistors marks an important step toward practical implementation in wireless infrastructure. NTT's December 2025 press release indicates that further development will focus on designing device structures for higher current and voltage operation to achieve higher output power. This will lead to tangible improvements in wireless communication services, such as broader coverage and faster speeds, ultimately benefiting various applications from enhanced mobile broadband to advanced IoT and autonomous systems.