A New SiC/Diamond Engineered Substrate Enabling High-Temperature (300 °C), High-Power (PDC,max≥ 60 W/mm) GaN HEMTs for RF and Power Applications

Here we propose and demonstrate a novel 4H-SiC/diamond engineered substrate capable of directly supporting high-quality, front-end MOCVD GaN epitaxy. The platform is realized by transferring a ~1 μm single-crystal 4H-SiC trimming layer onto a polycrystalline diamond substrate.

Through advanced bonding and trimming engineering, the 4H-SiC/diamond TBR is reduced to a record-low 8.45 m²·K·GW⁻¹ among all reported SiC/diamond interfaces. Leveraging this engineered substrate and pristine GaN-on-SiC epitaxy, the fabricated GaN HEMTs show exceptional high-temperature stability. We report the first demonstration of GaN HEMT dynamic stability at 300 °C, showing <3% current collapse under drain-lag pulse I-V measurements.