Research On The Microscopic Mechanism Of Graphene Growth By High Entropy Alloy Based CVD

As a new material emerging in recent years,graphene is ideally a two-dimensional material with only one atomic layer,composed of carbon atoms arranged regularly in a hexagonal lattice.Since its first manual peeling preparation in 2004,its excellent optical properties,mechanical properties,and electrical properties have immediately attracted widespread attention.However,since the performance of graphene is significantly affected by its quality,it is very important to produce high-quality single-layer graphene in an efficient,reliable,and controllable manner.Among the many preparation methods,chemical vapor deposition(CVD),which can accurately adjust various parameters in the growth substrate and the growth process,shows great potential in the direction of synthesis of large-area,high-quality single-layer graphene thin film.However,in actual production,the graphene prepared by this method still has many problems such as uneven layer number and poor repeatability,and it is always difficult to solve these problems by using traditional alloy substrates to grow graphene.Therefore,the research purpose of this thesis is to deeply analyze the growth mechanism of graphene,use it to design a highentropy alloy as a new substrate for graphene growth,study the effect of high-entropy alloy content on the number of graphene layers,and optimize the process parameters to prepare high-quality single-layer graphene film.In this paper,Cu Co Fe Ni Mn high-entropy alloy is used as the growth substrate of graphene,graphene was prepared by chemical vapor deposition method.The specific conditions of the four growth processes of carbon source decomposition,dissolution,diffusion and segregation were studied.The theoretical formulas were used to analyze the optimal alloy composition content and other parameters.High-quality single-layer graphene was prepared on the high-entropy alloy substrate.The main conclusion is that the growth mode of graphene on the high-entropy alloy substrate is segregation growth;In the decomposition stage of the carbon source,the method of increasing the hydrogen partial pressure and increasing the growth temperature can be used to accelerate the reaction rate of the carbon source,thereby increasing the graphene The preparation efficiency of graphene;The coverage of graphene and growth time are positively correlated,and the coverage of graphene can be improved by appropriately extending the growth time;The composition of the high-entropy alloy selected in this paper can be adjusted by adjusting the atoms of copper.The percentage content is used to adjust the average lattice constant of the high-entropy alloy,thereby adjusting the alloy's diffusion coefficient,etc.And then controlling the amount of carbon dissolution and segregation precipitation to adjust the number of graphene layers.The optimal copper content is 11% or less.High-quality single-layer graphene.The research method of this paper is the method of theoretical derivation combined with simulation and experimental demonstration.The control variable method is used to verify the relationship between the content of high-entropy alloy and the number of graphene layers,and to prepare high-quality single-layer graphene.Since so far,there are few reports on the research of high-entropy alloys as emerging substrates for graphene growth,so this research has great innovative significance and practical value.