Layer number and stacking order dependent thermal transport in molybdenum disulfide with sulfur vacancies

Recent theoretical works on two-dimensional molybdenum disulfide (${\mathrm{MoS}}_{2}$) with sulfur vacancies predict that the suppression of thermal transport in ${\mathrm{MoS}}_{2}$ by point defects is more prominent in monolayers and becomes negligible as the layer number increases. Here, we investigate experimentally the thermal transport properties of two-dimensional (2D) molybdenum disulfide crystals with inherent sulfur vacancies. We study the first-order temperature coefficients of interlayer and intralayer Raman modes of ${\mathrm{MoS}}_{2}$ crystals with different layer numbers and stacking orders. The in-plane thermal conductivity ($\ensuremath{\kappa}$) and total interface conductance per unit area ($g$) across the 2D material-substrate interface of mono-, bi-, and trilayer ${\mathrm{MoS}}_{2}$ samples are measured using micro-Raman thermometry. Our results clearly demonstrate that the thermal conductivity is significantly suppressed by sulfur vacancies in monolayer ${\mathrm{MoS}}_{2}$. However, this reduction in $\ensuremath{\kappa}$ becomes less evident as the layer number increases, confirming the theoretical predictions. No significant variation is observed in the $\ensuremath{\kappa}$ and $g$ values of $2H$ and $3R$ stacked bilayer ${\mathrm{MoS}}_{2}$ samples.