Study On The Thermal Transport Properties Of Graphene And Silicene

With the rapid development of nanoscience and technology,the problem of heat dissipation of materials has become a major constraint to the further reduction of the size of nanodevices,and the rise of new two-dimensional materials has attracted widespread attention due to its excellent thermal conductivity.In this paper,the thermal conductivity of graphene and silane nanoribbons was studied based on the molecular dynamics method,and the mechanism of thermal conductivity was explained by phonon density analysis.The main contents include:1.The thermal conductivity of zigzag silicene nanoribbons and armchair silicene nanoribbons was simulated and studied with the length.The simulation results show that the thermal conductivity of silicene nanoribbons increases with the increase of the length of silicene nanoribbons.As large as approximately a certain platform value fluctuates,the zigzag and armchair silicene nanoribbons platform values are 35 W/m K and 32 W/m K,respectively.At the same length,the thermal conductivity of the zigzag silicene nanoribbons is always higher than the thermal conductivity of the armchair silicene nanoribbons.It is shown that the thermal conductivity of silicene nanoribbons has obvious size effect and chirality effect.2.The effect of isotope doping on the thermal conductivity of silicene nanoribbons was simulated.Firstly,the effect of random doping 30 Si on the thermal conductivity of silicene nanoribbons was simulated at different concentrations.The simulation results show that as the concentration of doped isotope atoms gradually increases,the thermal conductivity first decreases and then gradually increases.U-shaped curve,then simulated the effect of isotope silicon atoms on the thermal conductivity of silicene nanoribbons during superlattice doping.The results show that at the same concentration of 40%,the superlattice doping(The relative thermal conductivity of pure silica decreases by 24%)leads to a lower thermal conductivity than random doping The relative thermal conductivity of pure silica decreases by 16%.3.In practical applications,the graphene nanoribbons was placed on the substrate.Based on this,the effect of the substrate on the thermal conductivity of graphene nanoribbons is simulated.First,the thermal conductivity of graphene nanoribbons with different lengths was calculated.It was found that the thermal conductivity of the graphene nanoribbons increases linearly with the increase of the graphene nanoribbon lengths.The graphene nanoribbons were obtained by reciprocal fitting.When the length approaches infinity,the thermal conductivity is about 5544 W/m K,and the results are similar to the experimental results.Then,when the substrate was acted on the graphene,it was found that the addition of the substrate caused the size effect of the graphene nanoribbon to be greatly suppressed.The phonon density analysis revealed that the addition of the substrate suppressed the vibration of the G peak.Amplitude,thereby reducing the thermal conductivity of the system.4?The thermal conductivity of the graphene nanoribbon under the effect of substrate inhomogeneous stress was simulated,and the projections were applied in the substrate.The influence of the height and width of the substrate projection on the thermal conductivity of the graphene nanoribbon was studied.The results show that the thermal conductivity of graphene nanoribbons gradually decreases with the increase of the height of the projections,while the width of the projections has almost no effect on the thermal conductivity of the graphene nanoribbons.