AI Article Synopsis

  • * Researchers used ultrafast electron diffraction to study phonon dynamics in specific heterobilayers with varying twist angles and found a fast heat transfer channel between layers.
  • * The study suggests that the rapid heat transfer happens due to a nonequilibrium state of phonons after initial electron interactions, offering insights for improving thermal management in these materials.

Article Abstract

Vertically stacked van der Waals (vdW) heterostructures exhibit unique electronic, optical, and thermal properties that can be manipulated by twist-angle engineering. However, the weak phononic coupling at a bilayer interface imposes a fundamental thermal bottleneck for future two-dimensional devices. Using ultrafast electron diffraction, we directly investigated photoinduced nonequilibrium phonon dynamics in MoS/WS at 4° twist angle and WSe/MoSe heterobilayers with twist angles of 7°, 16°, and 25°. We identified an interlayer heat transfer channel with a characteristic timescale of ~20 picoseconds, about one order of magnitude faster than molecular dynamics simulations assuming initial intralayer thermalization. Atomistic calculations involving phonon-phonon scattering suggest that this process originates from the nonthermal phonon population following the initial interlayer charge transfer and scattering. Our findings present an avenue for thermal management in vdW heterostructures by tailoring nonequilibrium phonon populations.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10807799PMC
http://dx.doi.org/10.1126/sciadv.adj8819DOI Listing

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