Engineering Heat Transport Across Epitaxial Lattice-Mismatched van der Waals Heterointerfaces

Artificially engineered2D materials offer unique physical propertiesfor thermal management, surpassing naturally occurring materials.Here, using van der Waals epitaxy, we demonstrate the ability to engineerextremely insulating thermal metamaterials based on atomically thinlattice-mismatched Bi2Se3/MoSe2 superlatticesand graphene/PdSe2 heterostructures with exceptional thermalresistances (70-202 m(2) K/GW) and ultralow cross-planethermal conductivities (0.012-0.07 W/mK) at room temperature,comparable to those of amorphous materials. Experimental data obtainedusing frequency-domain thermoreflectance and low-frequency Raman spectroscopy,supported by tight-binding phonon calculations, reveal the impactof lattice mismatch, phonon-interface scattering, size effects, temperature,and interface thermal resistance on cross-plane heat dissipation,uncovering different thermal transport regimes and the dominant roleof long-wavelength phonons. Our findings provide essential insightsinto emerging synthesis and thermal characterization methods and valuableguidance for the development of large-area heteroepitaxial van derWaals films of dissimilar materials with tailored thermal transportcharacteristics.