Revealing Defect-State Photoluminescence in Monolayer WS2 by Cryogenic Laser Processing

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• 作者：Zhengyu He ; Xiaochen Wang ; Wenshuo Xu ; Yingqiu Zhou ; Yuewen Sheng ; Youmin Rong ; Jason M. Smith ; Jamie H. Warner
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：June 28, 2016
• 年：2016
• 卷：10
• 期：6
• 页码：5847-5855
• 全文大小：647K
• 年卷期：0
• ISSN：1936-086X

文摘

Understanding the stability of monolayer transition metal dichalcogenides in atmospheric conditions has important consequences for their handling, life-span, and utilization in applications. We show that cryogenic photoluminescence spectroscopy (PL) is a highly sensitive technique to the detection of oxidation induced degradation of monolayer tungsten disulfide (WS₂) caused by exposure to ambient conditions. Although long-term exposure to atmospheric conditions causes massive degradation from oxidation that is optically visible, short-term exposure produces no obvious changes to the PL or Raman spectra measured at either room temperature or even cryogenic environment. Laser processing was employed to remove the surface adsorbents, which enables the defect states to be detected via cryogenic PL spectroscopy. Thermal cycling to room temperature and back down to 77 K shows the process is reversible. We also monitor the degradation process of WS₂ using this method, which shows that the defect related peak can be observed after one month aging in ambient conditions.