Graphene-Assisted Antioxidation of Tungsten Disulfide Monolayers: Substrate and Electric-Field Effect.

Kang, Kyungnam; Godin, Kyle; Kim, Young Duck; Fu, Shichen; Cha, Wujoon; Hone, James; Yang, Eui-Hyeok · Adv Mater · 2017

basic_science · Level V

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Abstract

Transition metal dichalcogenides (TMDs) have emerged as promising materials to complement graphene for advanced optoelectronics. However, irreversible degradation of chemical vapor deposition-grown monolayer TMDs via oxidation under ambient conditions limits applications of TMD-based devices. Here, the growth of oxidation-resistant tungsten disulfide (WS<sub>2</sub> ) monolayers on graphene is demonstrated, and the mechanism of oxidation of WS<sub>2</sub> on SiO<sub>2</sub> , graphene/SiO<sub>2</sub> , and on graphene suspended in air is elucidated. While WS<sub>2</sub> on a SiO<sub>2</sub> substrate begins oxidation within weeks, epitaxially grown WS<sub>2</sub> on suspended graphene does not show any sign of oxidation, attributed to the screening effect of surface electric field caused by the substrate. The control of a local oxidation of WS<sub>2</sub> on a SiO<sub>2</sub> substrate by a local electric field created using an atomic force microscope tip is also demonstrated.