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Covalent-bonding-induced strong phonon scattering in the atomically thin WSe2 layer
Young-Gwan Choi1,2, Do-Gyeom Jeong1, H I Ju1
1Department of Physics and Photon Science, School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju, 61005, South Korea.
Scientific Reports
|May 22, 2019
Summary
Heat dissipation in nano-devices is critical. Increasing layers of tungsten diselenide (WSe2) between metal and substrate significantly increases thermal boundary resistance, impacting device performance.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Heat dissipation in nano-devices utilizing 2D van der Waals materials is crucial for performance optimization.
- Nanoscale interfaces present significant challenges for efficient thermal transport.
Purpose of the Study:
- To investigate cross-plane thermal transport across WSe2 layers sandwiched between metal and substrate.
- To understand the impact of WSe2 layer number and metal choice on thermal boundary resistance (TBR).
Main Methods:
- Time-domain thermoreflectance (TDR) measurements were used to quantify thermal transport.
- Photoemission spectroscopy and optical second harmonic generation confirmed material properties.
Main Results:
- TBR significantly increases with the number of WSe2 layers (mono- vs. bi-layered).
- The effect of metal choice (Al, Au, Ti) on TBR depends on WSe2 thickness.
- Titanium (Ti) interfaces show improved metal-WSe2 conduction but increased WSe2-WSe2 resistance for bi-layered structures.
Conclusions:
- The WSe2 layer number and metal interface strongly influence thermal boundary resistance.
- Stronger metal bonding can lead to increased internal WSe2 thermal resistance, particularly in multi-layered systems.
- Metallization affects WSe2 valence states and symmetry, influencing thermal properties.
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