High Performance Millimeter-Wave AlGaN/GaN Fin-HEMT on Si Substrate

In this work, high performance Si-based AlGaN/GaN Fin-HEMT is fabricated for high power millimeter-wave applications. Superlattice-like dislocation annihilation layers with total thickness as thin as 286 nm are utilized to improve material crystalline quality and enhance heat dissipation. The optimized Si-based GaN heterojunction shows decreased dislocation density of 1.57×109cm-2and improved crystalline quality with (002) FWHM of 491 arcsec and (102) FWHM of 601 arcsec. The fabricated Fin-HEMT exhibits Ids.maxof 1323 mA/mm and Vkneeof 2.5 V. The current collapse is decreased to 9% owing to the suppressed peak electric field at the drain side of the gate foot by Fin structure. By measuring output characteristics degradation under high temperatures, Fin-HEMT shows less saturation current reduction, attributed to additional heat dissipation path provided by Fin structure. Further, fT/fmaxof 54/91 GHz are obtained for Fin-HEMT. Eventually, the millimeter-wave load-pull measurement shows that the fabricated Fin-HEMT delivers a record high output power density of 8.2 W/mm and decent power added efficiency of 45.2% together with improved linearity at 30 GHz and Vdsof 20 V, which demonstrates significant potential of Si-based GaN Fin-HEMT for high-power millimeter-wave applications.