I-Corps: Aluminum Nitride-based Power Transistors

Cornell University, Ithaca NY

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is to expand the limits of high-frequency, high-power signal amplification. This will be necessary for future wireless communications systems, including sixth generation (6G) wireless technology. 6G will require higher operation frequencies to enable much faster data transmission. As frequency increases, signal strength diminishes over much shorter distances. To offset this issue, signals must also be transmitted at higher powers to be able to carry the signal the necessary distance. The demand for this combination of high-power, high-frequency is expected to continue to grow, and the devices developed here are designed to achieve such performance. High-power, high-frequency data transmission is also an issue for self-driving cars. High-frequency signals enable detailed, real time mapping of a car's surroundings. High-power ensures the signal can travel through rain and fog, and return to the car before weakening beyond detection. The devices developed here can enable more detailed mapping at a longer range to make self-driving cars smarter and safer. This i-Corps project develops aluminum nitride (AlN) as a new platform for gallium nitride (GaN) transistors. The material advantages of an aluminum nitride platform over the traditional GaN platform are two-fold. AlN is much more electrically resistive than GaN, which prevents undesired leakage currents that hurt device performance. At the same time, the thermal conductivity of AlN is approximately 50% larger than that of GaN. The result is more efficient heat dissipation, enabling device operation at higher power. The research behind AlN-based power transistors is focused on crystal growth and device fabrication. Optimized crystal growth enables high quality AlN and GaN, improving device performance. The as-grown crystal is then processed into transistors, which requires state-of-the-art fabrication tools and refined processes. The AlN transistors have demonstrated high breakdown voltages when compared to state-of-the-art GaN-based transistors, a key measure for power performance. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.