Gonzalez-Munoz, Sergio and Evangeli, Charalambos and Xiao, Peng and Finch, Stuart and Sachat, Alexandros and Kolosov, Oleg (2024) Engineering heat transport across lattice-mismatched van der Waals heterostructures and superlattices. In: NANOSCALE AND MICROSCALE HEAT TRANSFER VIII, 2024-06-03 - 2024-06-07.
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Abstract
In contrast to naturally occurring materials, artificially engineered two-dimensional (2D) materials could offer new physical properties and functionalities, crucial for thermal management applications. Here, we have successfully employed wafer-scale heteroepitaxial growth to engineer thermal metamaterials with unique cross-plane thermal insulating properties. [1] Specifically, by creating thin films consisting of vertical lattice-mismatched van der Waals (vdW) heterostructures and superlattices, we have achieved exceptional thermal resistances, ranging from 70 to 202 m2K/GW, leading to ultralow cross-plane thermal conductivities (< 0.1 W/mK) at room temperature. Experimental data obtained using frequency-domain thermoreflectance and low-frequency Raman spectroscopy, supported by first principles density functional calculations, reveal the impact of interface-phonon scattering, size effects and lattice mismatch on cross-plane heat dissipation, uncovering different thermal transport regimes and the dominant role of long-wavelength phonons. Our findings, reveal the fundamentals of phonon transport mechanisms governing cross-plane heat dissipation in ultra-thin vdW films and provide valuable guidance for the development of wafer-scale engineered vdW stacks, ideal components in future three-dimensional (3D) heterogeneous electronics. References [1] E. Chavez-Angel et al., Nano Lett, 2023, 23, 6883-6891. Acknowledgment: We acknowledge support from the EU ERC grant TheMA - No. 101117958