Theoretical Study On Phonon Thermal Transport Properties Of Graphene And Silicene Nanostructures

In recent years,study on novel two-dimensional nanomaterials has promoted the miniaturization of electronic devices.The thermal transport properties of two-dimensional nanomaterials play an important role in the thermal management of nanodevices and the research of thermoelectric devices.In this paper,the non-equilibrium molecular dynamics method is used to study the phonon thermal transport properties of graphene-based and silicene-based nanostructures.The main findings include:1.The size and isotope doping effects of phonon thermal conductivity of silicene nanotubes were studied.It is found that within a limited length,the phonon thermal conductivity increases monotonically with the length of the nanotube,but the nanotube diameter has little effect on the phonon thermal conductivity.Both random doping and superlattice doping can significantly reduce phonon thermal conductivity.At the same doping concentration of 50%,the superlattice doping method causes a greater decrease in the phonon thermal conductivity of the silicene nanotubes than the random doping method does.As the superlattice doping period length of the silicene nanotube decreases,the phonon thermal conductivity firstly decreases,and then increases after the critical period length.This is due to that the competition between phonon interface scattering and phonon tunneling may result in the minimum phonon thermal conductivity at the critical period length.2.The effect of local strain formed by fullerene(C₆₀)and carbon nanotube?CNT?indented graphene on the phonon thermal conductivity of graphene nanoribbons was studied.As the indentation depth of C₆₀ and CNT increases,the phonon thermal conductivity of graphene nanoribbons continues to decrease.At the same indentation depth,increasing the number of C₆₀ leads to a greater decrease in phonon thermal conductivity of graphene nanoribbons.The interaction strength of C₆₀ and CNT with graphene nanoribbons has an important effect on the phonon thermal conductivity of graphene nanoribbons.The stronger surface interaction will cause larger local strain of graphene nanoribbons,so the enhancement of phonon scattering reduces the phonon thermal conductivity of graphene nanoribbons.3.The phonon thermal transport in graphene/silicene bilayer heterostructure was studied.It is found that the phonon thermal conductivity of the heterostructure is between the phonon thermal conductivities of single-layer graphene nanoribbon and the single-layer silicene nanoribbon.The strength of the interlayer interaction has an important effect on the phonon thermal conductivity of the heterostructure.As the interlayer interaction strength increases,the phonon thermal conductivity of graphene nanoribbons in the heterostructure decreases whereas the phonon thermal conductivity of silicene nanoribbons increases.