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Universal mechanical exfoliation of large-area 2D crystals.

Yuan HuangYu-Hao PanRong YangLi-Hong BaoLei MengHai-Lan LuoYong-Qing CaiGuo-Dong LiuWen-Juan ZhaoZhang ZhouLiang-Mei WuZhi-Li ZhuMing HuangLi-Wei LiuLei LiuPeng ChengKe-Hui WuShi-Bing TianChang-Zhi GuYou-Guo ShiYan-Feng GuoZhi Gang ChengJiang-Ping HuLin ZhaoGuan-Hua YangEli SutterPeter SutterYe-Liang WangWei JiXing-Jiang ZhouShi-Xuan Du
Published in: Nature communications (2020)
Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials.
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