【作者】 刘涛；

【导师】 苑泽伟；

【作者基本信息】 沈阳工业大学 ， 机械工程， 2023， 硕士

【摘要】 石墨烯作为新型二维纳米材料,具有出色的物化特性,被认为是替代硅成为下一代半导体的理想材料。然而,由于石墨烯的带隙为零,其在半导体领域的应用受到了很大的限制。为了克服这一问题,采用纳米探针切割石墨烯,加工成一定宽度的纳米带,便可以打开石墨烯的带隙。尽管目前已经出现了多种石墨烯加工方法,如纳米粒子刻蚀法、能量束加工法、掩膜光刻法以及AFM机械划切法等,但是这些方法都难以获得高质量的边缘结构。为了解决这一问题,本课题以AFM机械划切为基础,利用光催化辅助的方式切割石墨烯。通过分子动力学方法研究探针切割石墨烯的划切过程,从原子角度揭示纳米探针划切单层石墨烯切割边缘的结构演变机制,并且对划切过的石墨烯薄膜进行光催化氧化反应研究。主要研究内容如下:（1）通过Lammps建立纳米探针划切单层石墨烯薄膜的试验模型。分析不同划切深度、划切速度等参数对划切力、划切边缘形貌和原子等效应力的影响规律。模拟结果表明:随着划切深度的增加,石墨烯边缘变形程度增大,形成的划痕宽度增大,缺陷增多,探针受力增大。并且石墨烯边缘局部应力集中位置,会先出现裂纹破坏。划切速度对划切过程影响较小。因此,石墨烯塑性变形程度主要随划切深度的增加而增大。（2）通过原子力显微镜（AFM）对石墨烯薄膜进行划切试验。试验结果表明:探针下压载荷为2.7n N时,横向力（探针-石墨烯薄膜）约为1865n N,横向力（探针-硅基底）约为165n N。探针下压载荷为16.25n N时,横向力（探针-石墨烯薄膜）约为3588n N,横向力（探针-硅基底）约为567n N。说明随着下压载荷的增加,探针的横向力增大。并且划切过程中的探针横向力主要来自于探针与石墨烯之间的作用力。（3）通过光催化对石墨烯薄膜进行刻蚀试验,研究机械切割缺陷对石墨烯光催化氧化反应的促进作用。试验结果表明:能谱分析仪检测出了新的元素O,拉曼光谱在1350cm^-1出现了石墨烯的典型缺陷峰。说明光催化氧化反应发生在石墨烯表面,而具有机械切割边缘的石墨烯更容易发生光催化氧化反应。更多还原

【Abstract】 Graphene,a new two-dimensional nanomaterial with excellent physical and chemical properties,is considered to be an ideal material to replace silicon as the next generation of semiconductors.However,the application of graphene in the semiconductor field is greatly limited by its zero band gap.To overcome this problem,the band gap of graphene can be opened up by using nanoprobes to cut graphene and process it into nanoribbons of a certain width.Although several graphene processing methods have emerged,such as nanoparticle etching,energy beam processing,mask lithography and AFM mechanical scribing,all of these methods have difficulty in obtaining high-quality edge structures.In order to solve this problem,this project used AFM mechanical scribing as the basis for cutting graphene using a photocatalytic assisted approach.The structure evolution mechanism of graphene cut edges by nanoprobes was revealed from an atomic perspective by investigating the scribing process of graphene cut by probes through molecular dynamics methods,and the photocatalytic oxidation reaction of the scribed graphene films was studied.The main studies are as follows:（1）An experimental model of nanoprobe scribing of monolayer graphene films was established by Lammps.The effects of different scribing depths and scribing speeds on the scribing force,scribing edge shape and atomic isoelectric force were analysed.The simulation results showed that as the scribing depth increased,the graphene edge deformation increased,the scratch width increased,the number of defects increased and the force on the probe increased.And the local stress concentration location of graphene edge would first appear crack damage.Scribing speed had less influence on the scribing process.Therefore,the degree of graphene plastic deformation mainly increased with the increase of the scratching depth.（2）Scribing tests on graphene films were carried out by atomic force microscopy（AFM）.The results showed that the transverse force（probe graphene film）was about1865n N and the transverse force（probe silicon substrate）was about 165n N for a downward probe load of 2.7n N,and about 3588n N and 567n N for a downward probe load of 16.25n N.The transverse force of the probe increased with increasing downward pressure.The transverse force of the probe during the scribing process was mainly due to the force between the probe and graphene.（3）A photocatalytic etching test was carried out on graphene films to investigate the effect of mechanical cutting defects on the promotion of graphene photocatalytic oxidation.The experimental results showed that the new element O was detected by the energy spectrum analyser and the typical defect peak of graphene appeared in the Raman spectrum at 1350 cm^-1.This indicated that the photocatalytic oxidation reaction occurred on the surface of graphene and that graphene with mechanically cut edges was more prone to photocatalytic oxidation reactions.更多还原