News: Microelectronics
12 June 2025
Imec demonstrates record RF GaN-on-Si transistor performance
Imec of Leuven, Belgium has unveiled a gallium nitride (GaN) MOSHEMT (metal-oxide-semiconductor high-electron-mobility transistor) on silicon (Si) that achieves both record efficiency and output power for an enhancement-mode (E-mode) device operating at low supply voltage. In parallel, the firm also demonstrated a record-low contact resistance of 0.024Ω·mm, which is essential to further boost output power in future designs. Imec says that the results mark a crucial step toward integrating GaN technology into next-gen mobile devices, particularly those targeting the 6G FR3 band between 7 and 24GHz. The results are being presented at the 2025 Symposium on VLSI Technology and Circuits in Kyoto, Japan, June 8-12.
Imec’s GaN-on-Si E-mode MOSHEMT achieved a record 27.8dBm (1W/mm) output power and 66% power-added efficiency (PAE) at 13GHz and 5V. The result was obtained in a single device with an 8-finger gate layout, providing the gate width needed for high output power without requiring the combined power of multiple transistors. Imec says that the performance was enabled by combining a gate recess technique, used to shift the device into E-mode, with an InAlN barrier layer that offsets the performance loss from the thinned channel.
Image: Cross-sectional TEM image of the gate structure in imec’s GaN-on-silicon transistor. The image shows the finely etched gate region that enables the device’s E-mode operation.
In parallel to the device development, imec demonstrated a record-low contact resistance of 0.024Ω·mm, using a regrown n⁺(In)GaN layer maximizing current flow and minimizing power loss. While the result was obtained in a separate module, it is fully compatible with the E-mode transistor architecture. Simulations indicate that integrating this contact module could improve the output power density by 70%, meeting the performance target for 6G user equipment.
“Reducing contact resistance is crucial for pushing output power while keeping efficiency high,” said Alireza Alian, Principal Member of Technical Staff at imec. “Our next step is to integrate this contact module into the E-mode transistor and validate the expected gains in power and efficiency, bringing the device closer to real-world 6G applications.”
