Mechanical Exfoliation and Characterization of Single‐ and Few‐Layer Nanosheets of WSe2, TaS2, and TaSe2 |
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| Authors: | Hai Li Gang Lu Yanlong Wang Zongyou Yin Chunxiao Cong Qiyuan He Lu Wang Feng Ding Ting Yu Hua Zhang |
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| Affiliation: | 1. School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore, Website: http://www.ntu.edu.sg/home/hzhang/, Phone: +65‐6790‐5175;2. Fax: +65‐6790‐9081;3. Division of Physics and Applied Physics, School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore;4. Institute of Textiles and Clothing, Hong Kong Polytechnic University, Kowloon, Hong Kong, China |
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| Abstract: | Single‐ and few‐layer transition‐metal dichalcogenide nanosheets, such as WSe2, TaS2, and TaSe2, are prepared by mechanical exfoliation. A Raman microscope is employed to characterize the single‐layer (1L) to quinary‐layer (5L) WSe2 nanosheets and WSe2 single crystals with a laser excitation power ranging from 20 μW to 5.1 mW. Typical first‐order together with some second‐order and combinational Raman modes are observed. A new peak at around 308 cm?1 is observed in WSe2 except for the 1L WSe2, which might arise from interlayer interactions. Red shifting of the A1g mode and the Raman peak around 308 cm?1 is observed from 1L to 5L WSe2. Interestingly, hexagonal‐ and monoclinic‐structured WO3 thin films are obtained during the local oxidation of thinner (1L–3L) and thicker (4L and 5L) WSe2 nanosheets, while laser‐burned holes are found during the local oxidation of the WSe2 single crystal. In addition, the characterization of TaS2 and TaSe2 thin layers is also conducted. |
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| Keywords: | mechanical exfoliation WSe2 nanosheets Raman local oxidation |
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