Study On Interfacial Properties And Delamination Behavior Of Metal/Graphene Composite Structures

As the typical representative of van der Waals materials,graphene has aroused a wide range of research interests due to its excellent properties.In recent studies,metal-assisted exfoliation method has been identified as one of the most promising methods for exfoliating large areas of single-layer graphene.However,atomically flat surface of metal films is difficult to be prepared in experiments.Therefore,the surface roughness of metal has a great influence on the preparation of graphene by metal assisted exfoliation.In this study,the interfacial adhesion between graphene and metal are calculated,and the effect of substrate roughness on the evolution of configuration and interlayer delamination of multilayer graphene is analyzed by combining theoretical models with molecular dynamics simulations.The metal-assisted exfoliation of graphene and the peeling behavior of graphene from the substrate surface is also studied by MD simulation at the same time.The main research contents of this dissertation are as follows:(1)The interfacial adhesion energy between graphene and Au substrate is solved by combining continum mechanics theory with molecular dynamics simulation.Firstly,MD models of graphene with different layers and Au substrates with different morphologies are constructed.The effects of metal surface roughness,different conformal states of graphene and Au substrate,and the number of graphene layers on the interfacial adhesion are discussed.Secondly,the interfacial adhesion energy between graphene and Au substrate is obtained by the continum theory and compared with the results of molecular dynamics simulation.(2)The wrinkling and delamination behaviors of multilayer graphene membrane on rough substrates are studied in detail by combining energy method with molecular dynamics simulations.The effects of substrate surface roughness on the interfacial shear stiffness between graphene and Au substrate and the interlayer shear stiffness of graphene are investigated.The effect of rough Au substrate on the evolution of configuration and interlayer delamination of multilayer graphene is analyzed and the equilibrium configuration of multilayer graphene on rough Au substrate is obtained by theoretical calculation.The competition between the interfacial adhesion energy between graphene and substrate,the bending energy of graphene film and the shear strain energy is studied in detail.The results show that interlayer delamination occurs in a certain amplitude and wavelength range when the morphology of graphene films changes from partially-conformal state to fully-conformal state.The delamination behavior of multilayer graphene can also be regulated by applying strain to graphene in membrane when graphene membranes are in non-conformal state and fully-conformal state.(3)The metal-assisted exfoliation of graphene is studied by molecular dynamics simulation and experiment.In the molecular dynamics simulation,the influence of temperature,thickness of metal layer and other factors on the metal-assisted exfoliation of graphene is studied.At the same time,different thickness of metal films are obtained by electron beam evaporation in the experiment to study the influence of metal thickness on the metal-assisted exfoliation method.Finally,the effects of substrate surface roughness,peeling angle and other factors on the behavior of graphene membrane peeling from the substrate surface are explored by combining molecular dynamics simulations with theoretical analysis.In this dissertation,the wrinkling and delamination behavior of graphene on metal substrate and the metal-assisted exfoliation behavior of graphene are studied.The research results can provide theoretical support and technical guidance for the design and manufacture of graphene-based nanodevices.