Thermal transport across GaN/SiC interfaces is governed by phonon transmission. However, how distinct interfacial bonding configurations (IBCs) modify heat transport remains poorly quantified. Moreover, previous molecular simulations have been hindered by the limited accuracy of empirical interatomic potentials. In this work, a machine-learned neuroevolution potential is constructed to overcome these limitations. Based on this potential, we reveal that distinct IBCs decisively govern interfacial thermal conductance (ITC). Specifically, the ITC of the N-Si bonded interface is 237% higher than that of the Ga-Si bonded interface, with other IBCs yielding intermediate values. The enhanced ITC of the N-Si interface is attributed to a lower interfacial energy barrier, longer lifetime of low-frequency phonons, strong phonon spectral overlap, and the emergence of extended interfacial vibrational modes, all of which facilitate phonon transmission across the interface. In contrast, Ga-Si interfaces exhibit strongly localized vibrational modes arising from high-frequency phonon annihilation and phonon spectrum mismatch, leading to significantly reduced ITC. Furthermore, the introduction of interfacial phonon bridges (AlN) can increase ITC by 46–237% by mediating phonon coupling across mismatched vibrational spectra. However, this bridging effect is weak for N-Si interfaces where phonon matching is already favorable; notably, the ITC of the N-C IBC exceeds that of the N-Si case at small AlN thicknesses. The present results demonstrate that atomic-scale bonding configurations and phonon-bridge structures provide an effective route to modulate interfacial heat transport, offering microscopic insight into phonon-mediated thermal transmission in GaN/SiC heterostructures.

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• Interatomic & molecular potentials
• Lattice thermal conductivity
• Thermal transport
• Solid-solid interfaces
• Deep potential molecular dynamics
• Density functional calculations