Achieving optimal GaN/SiC interfacial thermal conductance via ultrathin alloy interlayers for high-power device cooling

Efficient heat dissipation across GaN/SiC interfaces is critical for the reliability of high-power devices, yet their interfacial thermal transport behavior remains insufficiently understood. Here, using a high-fidelity machine-learning interatomic potential, we perform systematic nonequilibrium molecular dynamics simulations to quantify and engineer the interfacial thermal conductance (ITC) of device-relevant SiC/GaN heterostructures. The results show that Al-rich Al x Ga 1− x N alloy interlayers and ultrathin amorphous layers can act as efficient phonon bridges for the strongly mismatched SiC/GaN interface by enhancing mid-frequency 5–15 THz transmission channels. In particular, a 1 nm Al 0.75 Ga 0.25 N interlayer markedly elevates the SiC/GaN ITC from ~ 243 to an unprecedented ~ 417 MW m −2 K −1 , corresponding to a 71% enhancement over the abrupt interface, whereas a 1 nm amorphous interlayer increases the ITC to ~ 384 MW m −2 K −1 . These enhancements in interfacial thermal conductance translate into clear device-level benefits. For instance, under a power density of 1 × 10 16 W m −3 , the peak channel temperature decreases from 478 K for an abrupt SiC/GaN interface to 427 K with a 1 nm amorphous interlayer, and further to 416 K with a 1 nm Al 0.75 Ga 0.25 N interlayer. This work provides functional interface-design guidelines for improving thermal management in GaN/SiC-based high-power devices.