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The Role of Oxygen Atoms on Excitons at the Edges of Monolayer WS2
journal contribution
posted on 2019-06-12, 00:00 authored by Zhenliang Hu, Jose Avila, Xinyun Wang, Jin Feng Leong, Qi Zhang, Yanpeng Liu, Maria C. Asensio, Junpeng Lu, Alexandra Carvalho, Chorng Haur Sow, Antonio Helio Castro NetoWe
clarify that the chemisorption of oxygen atoms at the edges
is a key contributor to the frequently observed edge enhancement and
spatial non-uniformities of photoluminescence (PL) in WS2 monolayers. Here we have investigated with momentum- and real-space
nanoimaging of the chemical and electronic density inhomogeneity of
WS2 flakes. Our finding from a large panoply of techniques
together with density functional theory calculation confirms that
the oxygen chemisorption leads to the electron accumulation at the
edges. This facilitates the trion dominance of PL at the edges of
WS2 flakes. Our results highlight and unravel the significance
of chemisorbed oxygen at the edges in the PL emission and electronic
structure of WS2, providing a viable path to enhance the
performance of transition-metal-dichalcogenide-based devices.