Heat sink efficiency investigation of silicon-on-diamond composite substrates for gallium nitride-based devices

In this work, thermometric measurements of gallium nitride-based ungated transistors on silicon-on-diamond composite substrates are performed. Their heat sink efficiency is compared with transistors made by standard technology on a silicon carbide substrates. Reducing of the surface temperature by more than 50$^\circ$C using new type of silicon-on-diamond composite substrates at dissipation power above 7 W is shown. The proposed approach is promising for increasing the output power and reliability of gallium nitride-based devices.