液相介质中激光辅助制备石墨烯及转移技术研究

发布时间：2018-03-22 23:30

本文选题：石墨烯　切入点：连续制备　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：石墨烯是一种单原子层厚度的新型碳材料,是碳原子以sp2杂化形成的二维蜂窝状薄膜材料,厚度仅有0.3554nm。石墨烯因为具有优异的光、电学性能而被学者们争相研究。激光的高能特性可以制备出性能优异的石墨烯,并且由于激光无污染,操作简单等独特的优势,引起越来越多的学者的关注。目前的研究大多集中在激光在化学气相沉积法(CVD)中的应用,对制备环境要求较高,工艺复杂,实现工业化生产成本较高,因此,有必要探讨高效经济的大规模制备石墨烯的新途径。本文研究了纳秒脉冲激光冲击水中石墨固体靶材制备石墨烯的新技术,创造性地在石墨靶材两端设置两个铜箔电极,形成水平方向的电场,利用电场力驱动激光冲击等离子体运动并沉积在铜箔表面,研究了不同的激光能量和不同的沉积时间对制备效率和质量的影响,并且对石墨烯的转移进行了进一步的研究,主要取得了以下创新性研究成果:(1)分析了纳秒脉冲激光的作用下石墨烯的生成机理,石墨晶体在极短的时间内吸收大量的激光能量,并且受到周围水介质的限制,热量无法迅速传输,在石墨表面形成高温高压的等离子体区,从而诱导石墨转变为石墨烯。转变过程主要可归纳为两个阶段:第一阶段为升温升压过程,石墨表层碳原子之间的共价键断裂成自由碳原子;第二阶段为降温降压过程,碳原子之间通过sp2杂化形成石墨烯。(2)探索了不同激光能量和沉积时间对制备的石墨烯质量的影响,激光功率密度为1.27x109W/cm2时,仅有极少量的石墨烯沉积在铜箔上,大部分为无定形碳;激光功率密度为2.55x109W/cm2时,随着沉积时间的增加,石墨烯的产生效率也明显提高;激光功率密度达到5.10x109W/cm2时,沉积15min发现得到的石墨烯面积较大,几乎遍布整个铜箔表面,层数比较均匀,效率达到40cm2/h,继续增加沉积时间会使石墨烯层数增加,褶皱等缺陷也会增加。(3)研究改进了石墨烯高质量转移技术,通过改进RCA清洗技术,将SC-1和SC-2溶液稀释到20:1:1对硅片进行清洗去除大的颗粒物和有机物,再采用激光空化产生脉动空泡,空泡的脉动运动产生等离子冲击波和微射流可以去除硅片表面的微纳米颗粒,使硅片的亲水性得到极大的改善,从而提高了石墨烯的转移质量。
[Abstract]:Graphene is a new kind of carbon material with the thickness of monatomic layer. It is a two-dimensional honeycomb film material formed by sp2 hybrid of carbon atom. The thickness of graphene is only 0.3554 nm. The high energy characteristic of laser can produce graphene with excellent performance, and because of its unique advantages, such as no pollution, simple operation and so on, More and more scholars pay more and more attention to it. At present, most of the researches focus on the application of laser in chemical vapor deposition (CVD), which requires high preparation environment, complex process and high cost to realize industrialized production. It is necessary to explore a new way to produce graphene on a high efficient and economical scale. In this paper, a new technique of preparing graphene from graphite solid target in water by nanosecond pulsed laser is studied. Two copper foil electrodes are creatively installed at the two ends of graphite target. A horizontal electric field was formed. The laser impingement plasma was driven by electric field force and deposited on the surface of copper foil. The effects of different laser energy and deposition time on the preparation efficiency and quality were studied. Furthermore, the transfer of graphene was further studied. The following innovative research results were obtained: 1) the formation mechanism of graphene under nanosecond pulse laser was analyzed. The graphite crystal absorbs a large amount of laser energy in a very short time. And limited by the surrounding water medium, the heat can not be transferred rapidly, forming a high temperature and high pressure plasma region on the surface of graphite. The transition process can be divided into two stages: the first stage is the process of temperature and pressure rise, the covalent bond between the carbon atoms in the surface layer of graphite breaks into free carbon atom, and the second stage is the process of decreasing temperature and reducing pressure. The effect of different laser energy and deposition time on the quality of graphene was investigated by sp2 hybridization between carbon atoms. When the laser power density was 1.27x109W/cm2, only a small amount of graphene was deposited on copper foil. When the laser power density is 2.55x109W/cm2, the yield efficiency of graphene increases obviously with the increase of deposition time, and when the laser power density reaches 5.10x109W/cm2, the area of graphene obtained by 15min deposition is larger. Almost all over the surface of copper foil, the number of layers is relatively uniform, and the efficiency is up to 40 cm 2 / h. If the deposition time continues to increase, the number of graphene layers will increase, and the defects such as folds will also increase.) the high quality transfer technology of graphene has been studied and improved. By improving the RCA cleaning technology, The SC-1 and SC-2 solution was diluted to 20:1:1 to remove the large particles and organic matter, then the pulsating cavitation was produced by laser cavitation. The plasma shock wave and micro-jet generated by the pulsating movement of the cavitation could remove the microparticles on the surface of the silicon wafer. The hydrophilicity of silicon wafer was greatly improved and the transfer quality of graphene was improved.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11

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