Thermal boundary conductance of CVD-grown MoS$_2$ monolayer-on-silica substrate determined by scanning thermal microscopy

TL;DR

This study measures the thermal boundary conductance of CVD-grown MoS$_2$ monolayers on silica using scanning thermal microscopy, revealing low conductance values and emphasizing the importance of boundary conductance in heat dissipation.

Contribution

It provides the first characterization of thermal boundary conductance of CVD-grown MoS$_2$ monolayers using SThM and demonstrates calibration extension from bulk to 2D materials.

Findings

Thermal boundary conductance is around 4.6 MW/m²K.

Values are within the lower range compared to exfoliated flakes.

Thermal boundary conductance dominates heat dissipation over in-plane conductivity.

Abstract

We characterize heat dissipation of supported molybdenum disulfide (MoS$_2$) monolayers grown by chemical vapor deposition by means of ambient-condition scanning thermal microscopy (SThM). We find that the thermal boundary conductance of the MoS$_2$ monolayers in contact with 300 nm of SiO$_2$ is around 4.6 $\pm$ 2 MW m$^{-2}$ K$^{-1}$. This value is in the low range of the values determined for exfoliated flakes with other techniques such as Raman thermometry, which span an order of magnitude (0.44-50 MW m$^{-2}$ K$^{-1}$), and underlines the dispersion of measurements. The sensitivity to the in-plane thermal conductivity of supported MoS$_2$ is very low, highlighting that the thermal boundary conductance is the key driver of heat dissipation for the MoS$_2$ monolayer when it is not suspended. In addition, this work also demonstrates that SThM calibration using different thicknesses of SiO$_2$, initially aimed at being used with bulk materials can be extended to 2D materials.