Enhanced Heat Dissipation of GaN RF Devices Based on Double-diamond Structure

In this paper, an enhanced heat dissipation structure, combining diamond substrate and diamond spreader, is considered for further improving the heat dissipation efficiency of GaNRF devices. The steady-state simulation is performed to analyze the thermal management ability of heat dissipation structures. The simulation is mainly focused on the comparisons of heat transfer capability and characteristics for double-diamond heat dissipation structure and the others, including GaN on SiC, GaN on diamond and GaN on SiC with diamond spreader. Simulation demonstrates that the junction temperature of device with double-diamond structure is 120°C, significantly lower than that on SiC substrate, since the coordination of diamond substrate and diamond spreader strengthens heat dissipation in both directions. The results also show that the heat dissipation performance of device is improved about 15 % by adding only 10 $\mu$m diamond spreader in double-diamond structure compared to that of single diamond substrate. In addition, the heat transfer ability could be further enhanced by optimizing the spreader thickness and the interface thermal resistance.