Surface amorphization enables phonon mode activation and enhanced thermal transport at 2D/3D van der Waals heterostructures

Efficient heat dissipation across van der Waals (vdW) interfaces between two-dimensional (2D) materials and three-dimensional (3D) substrates remains a fundamental bottleneck in nanoelectronic devices. Here, using molecular dynamics simulations, we demonstrate that introducing an atomically thin amorphous layer on the substrate surface dramatically enhances interfacial thermal transport at the hexagonal boron nitride/silicon dioxide (h-BN/SiO₂) interface. The interfacial thermal conductance increases by up to ~2.8 × compared with a smooth crystalline surface and can be further tuned by substrate roughness, interfacial coupling strength, and vacancy concentration. Spectral heat current and phonon mode analyses reveal a previously unexplored mechanism whereby amorphous surface topology activates intermediate and localized phonon modes, enabling efficient coupling between in-plane and out-of-plane phonons in h-BN and facilitating energy transfer into the substrate. This process redistributes high-frequency phonons toward low-frequency heat-carrying modes, induces a blueshift of acoustic phonons, and shortens phonon lifetimes through symmetry breaking and nonuniform vdW interactions. Our results establish surface amorphization as an effective and experimentally accessible strategy for engineering phonon transport at 2D/3D vdW interfaces, offering new opportunities for thermal management in 2D material-based nanoelectronics.