Thermal transport through GaN–SiC interfaces from 300 to 600 K

Silicon carbide is used as a substrate for high-power GaN devices because of its closely matched lattice spacing with GaN and its high thermal conductivity. In these devices, thermal resistance at the GaN–SiC interface is a bottleneck to heat flow, making this property an important factor in device design. In this letter, we report the first measurements of the thermal boundary conductance of epitaxial GaN grown directly on SiC without a transition layer. We find that the thermal boundary conductance increases from approximately 230 MW/m2K at 300 K to 330 MW/m2K at 600 K. Our measured values are in good qualitative agreement with the diffuse mismatch model for thermal boundary conductance and are in good quantitative agreement when we include a correction factor based on the ratio of Debye temperatures of the two materials. We also report the thermal conductivity of the GaN film, the thermal conductivity of 4H-SiC, and the thermal boundary conductance between Ni and GaN.