After an initial assessment of the structural and electronic properties of graphene, monolayer MoS2, and graphene/MoS2 bilayer hetero-structure, the temperature-dependent thermodynamic properties of graphene/MoS2 bilayer hetero-structure are examined by using density functional theory calculations. The structure, bandgap, partial density of states, and thermodynamic properties of graphene, monolayer MoS2 and graphene/MoS2 system are investigated and analyzed. Findings from the present study are in good agreement with the previously reported theoretical and experimental studies. Monolayer MoS2 and graphene form a stable Van der Waals heterostructure owing to their negative binding energy, and the system acts as a zero-bandgap semiconductor. Debye temperature and the heat capacity of graphene, MoS2 monolayer, and graphene/MoS2 system are calculated from phonon dispersion relations to be 2100 K, 600 K, and 1400 K, and 0.7 J/g.K, 0.218 J/g.K, and 0.46 J/g.K, respectively. Introduction of graphene into the MoS2 semiconductor is, therefore, found to improve the overall thermodynamic properties of the composite as graphene preserved its superior thermal properties. The findings will be beneficial to calculate thermal conductivity of the graphene/MoS2 heterostructure for minimizing the temperature effect in electronic or optoelectronic devices.
Keywords: Debye temperature; Density functional theory; Graphene-MoS2; Heat capacity; Phonon dispersion relations; Thermodynamic properties.