Sapphire-Based HEMT Hits 94 GHz for W-Band Power
The research-stage device uses a simplified fabrication process to reach high-frequency power targets at lower costs.
Updated on Oct. 26, 2026 in Semiconductors
Researchers have demonstrated a passivation-free Ga-polar AlGaN/GaN HEMT on a sapphire substrate capable of W-band operation at 94 GHz. This research-stage device offers a simplified fabrication process compared to N-polar alternatives while maintaining high-frequency performance metrics.
Why it matters
By utilizing sapphire substrates instead of more expensive silicon carbide, this approach aims to reduce manufacturing costs for millimeter-wave power applications. The design simplifies the epitaxial stack, potentially accelerating the development of affordable high-frequency communication hardware.
The device features a maximum oscillation frequency of 203 GHz and a current-gain cutoff of 127 GHz. It maintains a drain current density of 1.7 A/mm and a gate on/off ratio of 10^7, measured using continuous-wave load-pull testing at 94 GHz.
The details
The transistor uses a Ga-polar AlGaN/GaN (Aluminum Gallium Nitride/Gallium Nitride) architecture, which leverages a specific crystalline orientation to optimize electron mobility. Researchers implemented a recessed-gate design with a thin 5.5-nm barrier directly under the gate for control, while using a thicker 31-nm barrier in the access regions to minimize resistance. This structure avoids the need for passivation—the application of a protective insulating layer to the semiconductor surface—which typically adds complexity to the fabrication process.
Timeline
October 2026: Performance metrics for the Ga-polar HEMT were published.
The Tech Race
The semiconductor industry is currently racing to optimize AlGaN/GaN transistors for the W-band to support high-speed wireless networks. This design provides a potential path to lower costs compared to the established N-polar research programs.
This development is currently in the research stage and does not yet affect commercial products or current wireless workflows. Future integration into communication infrastructure depends on further testing of thermal stability and manufacturing yield.
The takeaway
This development demonstrates that sapphire-based gallium nitride transistors can achieve competitive W-band performance without complex passivation. Observers should track subsequent thermal testing and long-term reliability trials to determine the commercial viability of this epitaxial design.
Further reading
Explore ongoing advancements in high-frequency hardware development in the Semiconductors section.
Source note: This article includes information reported by MTT-S.
