Optical visualization of MoS2 grain boundaries by gold deposition
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The grain boundaries (GBs) in continuous films or domains of MoS2 are vital to its optical and electrical properties. Almost all previous approaches for GBs visualization are based on microscopy and spectroscopy and only effective for domains with less than several micrometers in size. Here we report a simple method for the visualization of large GBs in MoS2 surface by optical microscope. Gold was deposited on the MoS2 grown by chemical vapor deposition, and then the GBs could be observed by optical microscope. Upon gold deposition on MoS2, the entire GBs of large-area MoS2 were clearly visualized using this method. To verify the result, the GBs were also characterized via scanning electron microscopy, transmission electron microscopy and atomic force microscopy. It showed the small particles of gold were clustered together on GBs, which had a larger binding energy than the inner regions. The method is universal and allows for the nondestructive identification of the GBs in any two dimensional materials with large area.
Keywordsgrain boundaries gold deposition optical microscope single layer MoS2
近年来, 二硫化钼因其独特的光学和电学性能引起了人们的广泛关注. CVD法生长的MoS2上不可避免的存在很多晶界, 对其电学及光电性能具有很大影响. 以往观察晶界多采用电子显微镜和光谱, 且只能对几微米范围进行观察. 本文介绍了一种简单的沉积金的方法, 使MoS2表面的晶界在光学显微镜下可见. 与晶面内相比晶界处具有更高的结合能, 更有利于金颗粒的聚集, 沉积后退火使得金颗粒进一步变大, 足以在光学显微镜下可见. 用这种方法大面积MoS2晶界的始末端皆可以清楚地观察到. SEM, TEM, AFM的研究结果证实了以上方法的准确性. 该方法可用于任何大面积二维材料晶界的表征, 具有很强的普适性.
This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12010000), and the National Natural Science Foundation of China (21573253).
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