[Paper Review] Very High Interfacial Thermal Conductance in Fully hBN-Encapsulated MoS2 van der Waals Heterostructure

Fan Ye, Qingchang Liu+3 more|arXiv (Cornell University)|Feb 10, 2021

Thermal properties of materials42 references4 citations

TL;DR

This study demonstrates exceptionally high interfacial thermal conductance of 74 MW/m²K (supported) and 72 MW/m²K (suspended) between hexagonal boron nitride (hBN) and monolayer MoS2 in fully hBN-encapsulated van der Waals heterostructures. Using refined optothermal Raman spectroscopy and molecular dynamics simulations, the authors reveal that hBN encapsulation enables highly efficient heat dissipation, significantly outperforming MoS2 on other substrates.

ABSTRACT

We report experimental and computational studies of thermal transport properties in hexagonal boron nitride (hBN) encapsulated molybdenum disulfide (MoS2) structure using refined optothermal Raman techniques, and reveal very high interfacial thermal conductance between hBN and MoS2. By studying the Raman shift of hBN and MoS2 in suspended and substrate-supported thin films under varying laser power and temperature, we calibrate lateral (in-plane) thermal conductivity of hBN and MoS2 and the vertical interfacial thermal conductance in the hBN/MoS2/hBN heterostructure as well as the interfaces between heterostructure and substrate. Crucially, we have found that interfacial thermal conductance between hBN and encapsulated MoS2 is 74MW/m2K and 72MW/m2K in supported and suspended films, respectively, which are significantly higher than interfacial thermal conductance between MoS2 and other substrates. Molecular dynamics (MD) computations conducted in parallel have shown consistent results. This work provides clear evidence of significantly efficient heat dissipation in hBN/MoS2/hBN heterostructures and sheds light on building novel hBN encapsulated nanoelectronics with efficient thermal management.

Motivation & Objective

• To investigate thermal transport properties in fully hBN-encapsulated MoS2 van der Waas Heterostructures.
• To quantify interfacial thermal conductance between hBN and MoS2 for improved thermal management in 2D electronics.
• To compare thermal conductance in hBN-encapsulated MoS2 with MoS2 on other substrates.
• To validate experimental findings with parallel molecular dynamics (MD) simulations.
• To establish a reliable calibration method for lateral thermal conductivity and interfacial conductance using optothermal Raman techniques.

Proposed method

• Employed refined optothermal Raman spectroscopy to measure temperature-dependent Raman shifts in suspended and substrate-supported hBN/MoS2/hBN heterostructures under varying laser power.
• Calibrated lateral thermal conductivity of hBN and MoS2 by analyzing the Raman shift response to localized heating.
• Extracted vertical interfacial thermal conductance by modeling thermal resistance at the hBN/MoS2 and MoS2/substrate interfaces.
• Conducted parallel molecular dynamics (MD) simulations to validate experimental interfacial thermal conductance values.
• Used a combination of experimental data and theoretical modeling to decouple contributions from different interfaces in the heterostructure.
• Applied a thermal model based on heat diffusion and phonon transport to interpret Raman shift variations under thermal excitation.

Experimental results

Research questions

• RQ1 What is the interfacial thermal conductance between hBN and MoS2 in fully encapsulated heterostructures?
• RQ2 How does hBN encapsulation affect thermal transport compared to other substrates in MoS2 devices?
• RQ3 To what extent do experimental optothermal Raman measurements agree with molecular dynamics simulations for interfacial conductance?
• RQ4 What is the lateral thermal conductivity of hBN and MoS2 in the heterostructure configuration?
• RQ5 How does the thermal conductance vary between suspended and substrate-supported configurations?

Key findings

• The interfacial thermal conductance between hBN and MoS2 is 74 MW/m²K in substrate-supported heterostructures.
• The interfacial thermal conductance between hBN and MoS2 is 72 MW/m²K in suspended heterostructures.
• The measured interfacial thermal conductance between hBN and MoS2 is significantly higher than that observed for MoS2 on other substrates.
• Molecular dynamics simulations confirm the high interfacial thermal conductance values, showing strong agreement with experimental results.
• The lateral thermal conductivity of hBN and MoS2 was successfully calibrated using optothermal Raman techniques.
• The study demonstrates that hBN encapsulation enables highly efficient heat dissipation in 2D van der Waals heterostructures, supporting its use in next-generation nanoelectronics.