Visualizing Energy Transfer at Buried Interfaces in Layered Materials Using Picosecond X‐Rays

Understanding the fundamentals of nanoscale heat propagation is crucial for next‐generation electronics. For instance, weak van der Waals bonds of layered materials are known to limit their thermal boundary conductance (TBC), presenting a heat dissipation bottleneck. Here, a new nondestructive metho...

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Bibliographic Details
Published in:Advanced functional materials 2020-08, Vol.30 (34), p.n/a
Main Authors: Nyby, Clara, Sood, Aditya, Zalden, Peter, Gabourie, Alexander J., Muscher, Philipp, Rhodes, Daniel, Mannebach, Ehren, Corbett, Jeff, Mehta, Apurva, Pop, Eric, Heinz, Tony F., Lindenberg, Aaron M.
Format: Article
Language:English
Subjects:
Bonding strength
Energy transfer
Heat
heterogeneous integration
Irradiance
Layered materials
MATERIALS SCIENCE
Molecular dynamics
Nondestructive testing
Resistance
Room temperature
Sapphire
Substrates
Temperature dependence
thermal boundary conductance
Thermal strain
Time dependence
time-resolved x-ray diffraction
Transition metal compounds
transition metal dichalcogenides
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Summary:Understanding the fundamentals of nanoscale heat propagation is crucial for next‐generation electronics. For instance, weak van der Waals bonds of layered materials are known to limit their thermal boundary conductance (TBC), presenting a heat dissipation bottleneck. Here, a new nondestructive method is presented to probe heat transport in nanoscale crystalline materials using time‐resolved X‐ray measurements of photoinduced thermal strain. This technique directly monitors time‐dependent temperature changes in the crystal and the subsequent relaxation across buried interfaces by measuring changes in the c‐axis lattice spacing after optical excitation. Films of five different layered transition metal dichalcogenides MoX2 [X = S, Se, and Te] and WX2 [X = S and Se] as well as graphite and a W‐doped alloy of MoTe2 are investigated. TBC values in the range 10–30 MW m−2 K−1 are found, on c‐plane sapphire substrates at room temperature. In conjunction with molecular dynamics simulations, it is shown that the high thermal resistances are a consequence of weak interfacial van der Waals bonding and low phonon irradiance. This work paves the way for an improved understanding of thermal bottlenecks in emerging 3D heterogeneously integrated technologies. A new nondestructive method is presented to visualize heat transport in nanoscale 2D layered materials using time‐resolved X‐ray measurements of photoinduced thermal strain. This technique is extendable to any crystalline material, including those in confined geometries and active thermal devices, and directly captures the flow of energy across buried atomic interfaces.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.202002282