Study On Thermal Conductivity Of Low Dimensional Quantum Structure Materials Under Field Force

The further development of electrical and electronic technology has put forward higher requirements on the performance of components.Low dimensional materials,especially carbon thin film materials such as graphene,graphdiyne and so on,Become a new choice for chip manufacture because of its great specific surface area,high conductivity and excellent mechanical properties.But its heat conduction in local area has become a new technical problem,which restricts the development of microelectronic technology.Therefore,the research on the transport properties of low dimensional materials are more and more important.the control of thermal conductivity becomes the key to the development of microelectronic technology.Low-dimensional material,as one material that linearity is even lower than the electronic de Broglie wavelength,its carrier is limited to move in particular dimensions,its transport properties have a huge difference from bulk materials,which make it have unique physical properties.But at present,the research of low dimensional materials mainly focus on the electrical,optical and mechanical properties,the thermal conductivity of the material needs to be further explored.There are a lot of research methods of thermal conductivity,such as the theoretical analysis,represented by Boltzmann Transport Equations,and the experimental method,represented by Photothermal Deflection Method,but the special structure and size of the low dimensional materials have increased the difficulty of research.By comparison,molecular dynamics analysis can be used to study the thermal physical properties of materials better by calculating the configuration integral and solving the particle equations,so it is chosen as the simulation tool in this paper.Based on graphene as the research object,this paper adopts the analysis of dynamics simulation method to study the transport properties.Firstly,the model of single layer graphene nanoribbon was established,the influence factors to the thermal conductivity,such as the size,the chirality and the temperature,has been studied by the simulation method using non equilibrium state.It founds that the thermal conductivity of graphene nanoribbons exists size effect,the thermal conductivity of graphene has a positive correlation with the length and width in a certain range,this is determined by the phonon mean free path and the boundary conditions,which is consistent with the classical phonon theory;Different chiral graphenes also exist difference.Because of the differences of boundary transmission speed and transmission mechanism,the thermal conductivity of zigzag graphene(ZGNRs)was 20%higher than that of armchair graphene(AGNRs)with the same size;in addition,the temperature will make the thermal conductivity shows a tendency of first increase and then decrease.Besides,the selection of simulation parameters such as the potential function and boundary conditions will affect the simulation results as well.Then the factors such as defects and the field force were taken into analysis.It shows that the defect position has little effect on the thermal conductivity of graphene,but the increase of the defect density will lead to a fast decrease of the thermal conductivity;The field force has great influence on the thermal conductivity,it can be increased to 3 times of that without the field force under the simulated conditions;the field force of the vertical heat flux is slightly higher than that of the heat flux;The increase of the field force frequency can result in the fluctuation of the thermal conductivity value,but the general trend of the two presents positive correlation,i.e.,the higher the frequency,the greater the thermal conductivity.