Analytical insight into the lattice thermal conductivity and heat capacity of monolayer MoS2

• Semi-analytic solution of lattice thermal conductivity of the monolayer MoS2 is proposed.
• The in-plane and the out-of-plane acoustic modes are considered.
• Closed-form expressions of the mode specific heat capacities have been formulated.
• Effective scattering includes the phonon-boundary scattering, along with the intrinsic one.
• The model could be useful to look into the electro-thermal behaviour of two dimensional TMDs.

We report, a detailed theoretical study on the lattice thermal conductivity of a suspended monolayer MoS2, far beyond its ballistic limit. The analytical approach adopted in this work mainly relies on the use of Boltzmann transport equation (BTE) within the relaxation time approximation (RTA), along with the first-principles calculations. Considering the relative contributions from the various in-plane and out-of-plane acoustic modes, we derive the closed-form expressions of the mode specific heat capacities, which we later use to obtain the phonon thermal conductivities of the monolayer MoS2. Besides finding the intrinsic thermal conductivity, we also analyse the effect of the phonon-boundary scattering, for different dimensions and edge roughness conditions. The viability of the semi-analytic solution of lattice thermal conductivity reported in this work ranges from a low temperature (T∼30 K) to a significantly high temperature (T∼550 K), and the room temperature (RT) thermal conductivity value has been obtained as 34.06Wm−1K−1 which is in good agreement with the experimental result.