Simulation Optimization of Embedded Microchannel Heat Sink for GaN HEMTs

As the power density of Gallium Nitride (GaN)-based devices increases, heat dissipation becomes a major challenge. Embedded micro-channel heat sink have attracted much attention because of their high heat dissipation performance. In this paper, a GaN High-Electron-Mobility Transistor (HEMTs) model is established, and the effects of micro-channel geometry parameters (depth, width, spacing) and cooling fluid rate on heat dissipation performance are investigated by COMSOL Multiphysics. The pressure drop across the coolant inlet and outlet needs to be balanced while achieving effective cooling. With this trade-off, an optimal combination of microfluidic channel dimensions was obtained: depth of 200 μm, width of 100 μm, spacing of 80 μm. An increase in the flow rate of the cooling fluid generally corresponds with enhanced heat dissipation capabilities. Again, there is a trade-off between coolant pressure drop and flow rate to achieve high heat dissipation performance. Finally, in conjunction with the optimality conditions obtained from the simulation, the maximum temperature of the device is 135.5 °C, which is 45.5 °C lower than that of the device without embedded microchannel structure. In addition, the effects of different substrates on the temperature of the device are simulated. Embedded microchannels based on diamond substrates maximize the potential of liquid cooling. This paper provides theoretical and experimental basis for the design and optimization of embedded microchannel cooling structure, which is helpful to improve the heat dissipation performance of GaN devices.