Molecular Dynamics Study On Heat Transport Of 2D Heterojunction

Recently,two-dimensional heterojunctions prepared experimentally from a single layer of two-dimensional material have attracted special attention.The two-dimensional materials such as graphene can form a two-dimensional heterojunction inside the layer through strong chemical bonds,and they can also partially overlap,forming a two-dimensional heterojunction between layers through Van der Waals forces.This new two-dimensional heterostructure,unlike traditional heterojunctions,provides an ideal platform for new device design and artificial physical cutting.However,as the device size gets smaller and smaller,the heat transfer and heat dissipation issues constrain the development and application of related devices.Naturally,the influence of the interface structure of the novel two-dimensional heterojunction on the heat transfer and heat dissipation of the device as well as its mechanism has aroused great concern.In this dissertation,we construct a two-dimensional intra-layer heterojunction and an inter-layer Van der Waals two-dimensional heterojunction device model based on two-dimensional materials such as graphene.Using non-equilibrium molecular dynamics and an applied temperature gradient method,we explored the interface heat transfer characteristics of the heterojunction devices and its physical mechanism.Some significant results have been obtained.The main points of this paper are as follows:1.In Chapter Ⅰ,we introduce the research of nanomaterials and heat transport problems,and describe their significance and application prospects.2.In Chapter Ⅱ,we explained the development process of molecular dynamics and its basic principles and methods,and gave a brief introduction to the theory and formulas that need to be understood in computational simulation.3.A two-dimensional heterojunction model in a graphene/graphene-like layer was constructed,the dependence of the heat transport properties of heterojunctions on the elemental mass and the atomic potential of two-dimensional materials was explored,and a series of scaling laws were revealed.In addition,an actual two-dimensional heterojunction device model was constructed to explore the effects of material element mass and atomic potential on its heat transport performance.The validity of the scaling laws of the previous theoretical model was evaluated,which provides an effective method for the assessment of the heat transport performance of two-dimensional heterostructures4.An inter-layer two-dimensional Van der Waals graphene heterojunction model was constructed.The intrinsic correlation between the thermal transport properties and the geometric parameters of the two-dimensional heterojunction was studied.The overall thermal resistance of the interface and the overall length of the heterojunction were obtained.The obtained results provide guidance for the design of two-dimensional heterojunction devices and the regulation of their thermal performance.5.In Chapter V,we summarize the influence of both the two-dimensional intra-layer heteroj unction with strong chemical bonding and the two-dimensional inter-layer Van der Waals heterojunctions on the heat transport.Other factors affecting the heat transport of two-dimensional heterojunctions,such as interface lattice distortions,stress,and so on,would be explored in our future works.