Low-Temperature Substrate Bonding Technology for High Power GaN-on-Diamond HEMTs

We report the first demonstration of GaN-on-diamond RF power transistors produced by low-temperature substrate bonding technology. GaN high-electron-mobility transistors (HEMTs) are lifted from the original SiC substrate post fabrication and transferred onto high-quality polycrystalline diamond with thermal conductivity of 1,800 - 2,000 W/mK. Resulting GaN-on-diamond HEMTs demonstrated DC current density of 1.0A/mm, transconductance of 330mS/mm, and RF output power density of 6.0W/mm at 10GHz (CW). Finite-element thermal modeling indicates GaN-on-diamond technology based on low-temperature substrate bonding is capable of 3X increased power per area compared to conventional GaN-on-SiC devices.