Control of Radiation Damage in MoS2 by Graphene Encapsulation
Recep Zan, Quentin M Ramasse, Rashid Jalil, Thanasis Georgiou, Ursel Bangert, Kostya S. Novoselov
备注：
This document is the Submitted Manuscript version of a Published Work that appeared in final form in ACS Nano,copyright \c{opyright}[2013] http://pubs.acs.org/doi/abs/10.1021/nn4044035
Recent dramatic progress in studying various two-dimensional (2D) atomic crystals and their heterostructures calls for better and more detailed understanding of their crystallography, reconstruction, stacking order, etc. For this, direct imaging and identification of each and every atom is essential. Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) are ideal, and perhaps the only tools for such studies. However, the electron beam can in some cases induce dramatic structure changes and radiation damage becomes an obstacle in obtaining the desired information in imaging and chemical analysis in the (S)TEM. This is the case of 2D materials such as molybdenum disulfide MoS2, but also of many biological specimens, molecules and proteins. Thus, minimizing damage to the specimen is essential for optimum microscopic analysis. In this letter we demonstrate, on the example of MoS2, that encapsulation of such crystals between two layers of graphene allows for a dramatic improvement in stability of the studied 2D crystal, and permits careful control over the defect nature and formation in it. We present STEM data collected from single layer MoS2 samples prepared for observation in the microscope through three distinct procedures. The fabricated single layer MoS2 samples were either left bare (pristine), placed atop a single-layer of graphene or finally encapsulated between single graphene layers. Their behaviour under the electron beam is carefully compared and we show that the MoS2 sample 'sandwiched' between the graphene layers has the highest durability and lowest defect formation rate compared to the other two samples, for very similar experimental conditions.
Engineering 2D material exciton lineshape with graphene/h-BN encapsulation
Institute of Semiconductors, Chinese Academy of Sciences（中国科学院半导体研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Indian Institute of Science Education and Research（印度科学教育与研究学院）；National Taiwan University of Science and Technology（台湾科技大学）；Imperial College London（帝国理工学院）；National Institute for Materials Science（日本国立材料研究所）；Brno University of Technology（布尔诺理工大学）
Deep-UV bleaching of charge disorder in encapsulated graphene
University of Manchester（曼彻斯特大学）；National Graphene Institute, University of Manchester（国家石墨烯研究所，曼彻斯特大学）；National Institute for Materials Science（国立材料科学研究所）；University of Lancaster（兰卡斯特大学）
Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic Crystals
六方氮化硼是迄今为止唯一允许石墨烯器件表现出微米级弹道输运的基材。其他原子级平坦晶体能否用作制造优质石墨烯异质结构的基底？在这里，我们报告我们寻找替代基板。发现通过用二硫化钼或二硫化钨和hBN包封石墨烯制造的器件表现出约60，000 cm-1 $^{2}$ s $^{-1}$的一致高载流子迁移率。相比之下，用原子级平坦的层状氧化物（例如云母、铋锶钙铜氧化物和五氧化二钒）进行封装导致具有~ 1，000 cm $^{2}$ s $^{-1}$的迁移率的石墨烯器件的质量异常低。我们将这种差异主要归因于石墨烯、hBN和过渡金属二硫属化物之间界面处发生的自清洁。表面污染物聚集成大的口袋，允许界面的其余部分变得原子级清洁。对于原子级平坦的氧化物衬底上的石墨烯，不发生清洁过程。
Up/down-conversion of infrared light by few-layer graphene polytypes
National Graphene Institute, University of Manchester（国家石墨烯研究所，曼彻斯特大学）；Department of Physics & Astronomy, University of Manchester（曼彻斯特大学物理与天文系）；Department of Physics, University of Osaka（大阪大学物理系）；Center for Integrated Science and Humanities, Fukushima Medical University（福岛医科大学综合科学与人文学中心）；Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）
N.N. Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences（俄罗斯科学院 N.N. 谢苗诺夫化学物理联邦研究中心）；Plekhanov Russian University of Economics（普列汉诺夫俄罗斯经济大学）
Negligible electronic contribution to heat transfer across intrinsic metal/graphene interfaces
尽管金属接触的高热导率（即，低热阻）对于石墨烯器件的热管理很重要，但先前报道的金属/石墨烯界面的热导率都相对较低，仅为20-40 MW m $^{-2}$ K $^{-1}$。改善金属/石墨烯界面的热导率（$G$）的一种可能途径是通过电子的额外热传导，因为石墨烯可以容易地被金属掺杂。在本文中，我们评估的电子热传导金属/石墨烯界面通过测量Pd/transferred graphene（trG）/Pd界面的热导率，无论是热蒸发或射频（rf）磁控溅射制备，在80至500 K的宽温度范围内。我们发现，对于热蒸发法制备的样品，Pd/trG/Pd的热导率为42 MW m $^{-2}$ K $^{-1}$ .热导率仅微弱地取决于温度，这表明热主要由声子携带穿过本征Pd/石墨烯界面。然而，对于Pd/trG/Pd样品的顶部Pd膜沉积的射频磁控溅射，我们观察到一个显着的增量的热导从42 MW m $^{-2}$ K $^{-1}$的固有值为300 MW m $^{-2}$ K $^{-1}$，和$G$大致成正比于$T$。我们将热导的增强归因于在溅射过程中通过在石墨烯中形成的原子级针孔由电子进行热传输的附加通道。因此，我们得出结论，电子在金属和原始石墨烯的本征界面之间的热传导中起着微不足道的作用，并且电子的贡献只有在石墨烯被损坏时才是实质性的。
