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Novel techniques to produce and deposit n-layer graphene: Their physical properties.

机译：生产和沉积n层石墨烯的新技术：其物理性质。

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摘要

A novel technique "electrostatic deposition of graphene" has been developed for transferring graphene (one atomically thick graphite layer) onto desired substrate. This method of graphene transfer is unique in the sense that the high voltage applied between the graphite and the substrate appears to overcome the repulsive part of the van der Waals interaction at small separation and thus produce monolayer thick graphene. In order to get a high-yield deposition of the graphene, the surface of the substrate can be modified. For example a corrugated silicon microfabricated trenches can be used instead of a flat silicon substrate. In this case the effective electric field is enhanced due to the sharp edges. The deposition involves no chemical additives eliminating a major source of contamination that previously had been difficult to remove and can be deposited with a specified number of layers, enabling the tuning of electronic properties More interestingly, this method can control (i) the number of layers by tuning the applied electric field; and (ii) lateral size of the graphene by depositing under controlled vacuum.;Also, the problem of fabrication graphene ribbons was solved. The gas jet impactor was made. The impactor produces the graphene ribbons of the controlled width. The width of the ribbons depends on the pressure difference between two chambers (gas velocity that carries metal clusters) and the metal type (indium, gallium, mercury) that can be used for the bombardment of graphite surface. Then employing electrostatic deposition technique the dislocated graphene ribbons can be transferred to the substrate. A detailed study was performed on different number of layers graphene sheets and ribbons by Atomic Force Microscopy, Raman Spectroscopy, Scanning Electron Microscopy and Optical Microscopy. Certain signature peaks for graphene were observed by using Raman spectroscopy and with combination of an AFM measurement that clearly identified the number of graphene layers deposited on substrate.;The investigation of the electric transport properties of the graphene reveals that graphene ribbons deposited on Si/SiO2 substrate and back gated shows p-type behavior under ambient conditions. This behavior can be reversed upon annealing at high temperature in a vacuum. N-type behavior under degassed conditions is attributed as due to the charge transfer from surface states on SiO2 to graphene. P-type behavior under ambient is believed to be due to electrochemically mediated charge transfer from graphene to oxygen. Charge transfer effects were observed when the degassed graphene was exposed to N2O and NH3.;It was demonstrated that atomic layers of graphene have stiffness E ∼ 1 TPa. These results show that single atomic sheets can be integrated with microfabricated structures to create a new class of atomic scale membrane-based devices.
机译：已经开发出一种新颖的技术“石墨烯的静电沉积”，用于将石墨烯（一个原子厚的石墨层）转移到所需的衬底上。这种石墨烯转移方法的独特之处在于，在石墨和基材之间施加的高电压似乎可以克服小间距范德华相互作用的排斥部分，从而产生单层厚的石墨烯。为了获得高产率的石墨烯沉积，可以对基底的表面进行改性。例如，可以使用波纹状的硅微制造沟槽代替平坦的硅衬底。在这种情况下，由于锋利的边缘，有效电场得以增强。沉积过程无需化学添加剂，从而消除了以前难以清除的主要污染源，并且可以沉积指定的层数，从而可以调节电子性能。更有趣的是，该方法可以控制（i）层数通过调节施加的电场； （ii）通过在受控的真空下沉积来石墨烯的横向尺寸。；此外，解决了制造石墨烯带的问题。制备了气体冲击器。撞击器产生具有受控宽度的石墨烯带。条带的宽度取决于两个腔室之间的压力差（携带金属簇的气体速度）和可用于轰击石墨表面的金属类型（铟，镓，汞）。然后，采用静电沉积技术，可以将位错的石墨烯带转移到衬底上。通过原子力显微镜，拉曼光谱，扫描电子显微镜和光学显微镜对不同层数的石墨烯片和碳带进行了详细的研究。通过使用拉曼光谱并结合AFM测量观察到了石墨烯的某些特征峰，可以清楚地识别出沉积在基板上的石墨烯层的数量。;对石墨烯的电传输性质的研究表明，沉积在Si / SiO2上的石墨烯带衬底和背栅在环境条件下显示p型行为。在真空中高温退火后，这种现象可以逆转。脱气条件下的N型行为归因于电荷从SiO2上的表面态转移到石墨烯。据信在环境下的P型行为归因于从石墨烯到氧的电化学介导的电荷转移。当脱气的石墨烯暴露于N2O和NH3时观察到电荷转移效应。证明了石墨烯的原子层的刚度E〜1 TPa。这些结果表明，单个原子片可以与微细结构集成在一起，以创建一类新的基于原子尺度的膜基器件。

著录项

  • 作者

    Sidorov, Anton N.;

  • 作者单位

    University of Louisville.;

  • 授予单位 University of Louisville.;
  • 学科 Engineering Electronics and Electrical.;Physics Condensed Matter.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;工程材料学;
  • 关键词

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