石墨烯的结构缺陷识别与检测

With the ongoing research upsurge in graphene, there are significant efforts to develop large-scale integrated graphene devices for application in micro-electronic field and photo-electronic field. However, it is always unsatisfactory from an engineering point of view, as the performance of the integrated graphene devices are significant different from each other. The existing microstructures of structural defects and grain boundaries have dramatically influenced the electronic and mechanical behavior of graphene. Therefore, how to quantify these invisible structural defects and prepare high-quality graphene with fewest defects is the most important thing we need to solve out..This project is just focused on the detection and identification of structural defects in graphene. In this project, we will try to develop a widely applied technique to detect the structural defects in all kinds of graphene samples. The main study content includes these three parts: 1) Developing a conventional technique for defect detecting based on the anisotropic etching technique and atomic force microscopy. 2) Defect detecting for epitaxial graphene on silicon carbide and CVD synthesized graphene on copper. Trying to make clear the defect affected physical properties (such as electronic transport, phonon scattering) of graphene. 3) Analyzing the formation mechanism of defects and grain boundaries during the growth process, and trying to optimize the growth parameters to prepare high-quality graphene with fewer defects..The promotion of this project could simplify the complex problem by enlarging the microscopic view into macro-level, thus provide the qualitative and quantitative analysis method for confirming the intrinsic defects, grain boundary and crystal orientation of graphene. All these results could provide experimental support for revealing the intrinsic transport properties of graphene based device. The design used in this project is simple, clean, convenient and low cost, thus can be completely used for industrial detection technology.

随着石墨烯在应用领域的逐渐拓展，如何定量检测石墨烯的结构缺陷，理解缺陷对载流子迁移率等的影响，制备出缺陷密度低的高质量石墨烯是目前亟待解决的关键问题。本项目立足于石墨烯的结构缺陷识别与检测，拟开发出一套可广泛应用于任意石墨烯样品缺陷检测的工艺方法，主要的研究内容包括： 1）结合氢等离子体各向异性刻蚀技术和原子力显微技术，发展一种可用于石墨烯缺陷检测的常规技术。2）检测碳化硅热解外延石墨烯和化学气相沉积石墨烯等样品的缺陷，并研究缺陷对石墨烯本身物理性能（如电学输运、声子散射等）的影响。3）分析缺陷产生的原因、机理，研究优化生长工艺的参数。.本项目的开展可将复杂的问题简单化，微观的问题宏观化，定性定量的分析石墨烯的本征缺陷、晶界与晶向，从而为揭示石墨烯基器件的输运性质提供了实验支持。本项目所采用的方法与设备均简单好用、成本低廉，结果直观明了，完全可用于工业化检测技术之中。

缺陷的存在对于石墨烯结构来说总是无法避免的，随着石墨烯在应用领域的逐渐拓展，如何定量检测石墨烯的结构缺陷，理解缺陷对载流子迁移率等的影响，实现对石墨烯缺陷的调控与应用具有重要的意义。本项目立足于石墨烯的结构缺陷识别与检测，开发出了一套可广泛应用于任意石墨烯样品缺陷检测的工艺方法。我们分别对机械剥离的石墨烯与碳化硅上外延石墨烯进行了缺陷密度检测与晶向判定，并系统研究了缺陷散射对石墨烯输运性质的影响。在此基础之上，我们尝试从应用的角度来对石墨烯的结构缺陷进行调控。我们发展了一种两步法可控缺陷制造技术-氧等离子体引入缺陷，氢等离子体刻蚀放大缺陷-来加工密度、尺寸可控的石墨烯纳米孔结构，这种方法简单高效，最小的石墨烯纳米孔尺寸只有 2 nm，可以与聚焦电子束轰击得到的石墨烯纳米孔尺寸相媲美。利用这种可控缺陷制造技术，我们还可以仅在顶层进行缺陷引入，并保留顶层以下的晶体结构完整性，这样就实现了高质量石墨烯单原子层的逐层减薄技术。利用该技术，我们发展了一种干净可控的全石墨烯基器件的制备加工手段，器件间的互联线用多层石墨烯实现，获得了室温下非常低的接触电阻35 ± 20 欧姆•微米，为进一步提高石墨烯器件的性能与稳定性打下了基础。