Esfandiari Mehrnaz, Mohajerzadeh Shams
Thin Film and Nanoelectronic Lab, School of Electrical and Computer Eng, College of Engineering, University of Tehran, Tehran, Iran.
Nanotechnology. 2019 Oct 18;30(42):425204. doi: 10.1088/1361-6528/ab31b5. Epub 2019 Jul 13.
We report a facile method to realize large area two-dimensional tungsten disulfide nanosheets. The formation of such large WS sheets is feasible through sonication in water and dimethyl-sulfoxide (DMSO) solutions, leading to well-separated mono and few layer flakes. The exfoliation has been improved by extensive immersion in near-freezing water prior to probe sonication and subsequent addition of DMSO. By applying oxygen plasma before exfoliation, the size and distribution of sheets become more uniform and larger mono and double-layered structures with sizes of the order of 1 μm are achieved. Different analyses such as SEM, TEM, AFM, DLS and Raman spectroscopy have been employed to understand the mechanism of the exfoliation and study the effects of various parameters such as water temperature, duration and plasma power. The optical properties of WS sheets have been examined with a 532 nm laser illumination and demonstrate superior responsivity and detectivity of 0.59 A W and 6.5 × 10 cm Hz W, respectively.
我们报道了一种实现大面积二维二硫化钨纳米片的简便方法。通过在水和二甲基亚砜（DMSO）溶液中进行超声处理，形成这种大面积的WS片是可行的，从而得到分离良好的单层和少层薄片。在进行探头超声处理之前，将样品长时间浸泡在近冰点的水中，随后加入DMSO，可改善剥离效果。通过在剥离之前施加氧等离子体，薄片的尺寸和分布变得更加均匀，并且可以获得尺寸约为1μm的更大的单层和双层结构。我们采用了扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）、动态光散射（DLS）和拉曼光谱等不同分析方法，以了解剥离机理并研究诸如水温、持续时间和等离子体功率等各种参数的影响。利用532nm激光照射对WS片的光学性质进行了检测，其响应度和探测率分别为0.59 A W和6.5×10 cm Hz W，表现出优异的性能。
