Remote Plasma Oxidation and Atomic Layer Etching of MoS2

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• 作者：Hui Zhu ; Xiaoye Qin ; Lanxia Cheng ; Angelica Azcatl ; Jiyoung Kim ; Robert M. Wallace
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：July 27, 2016
• 年：2016
• 卷：8
• 期：29
• 页码：19119-19126
• 全文大小：587K
• 年卷期：0
• ISSN：1944-8252

文摘

Exfoliated molybdenum disulfide (MoS<sub>2sub>) is shown to chemically oxidize in a layered manner upon exposure to a remote O<sub>2sub> plasma. X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and atomic force microscopy (AFM) are employed to characterize the surface chemistry, structure, and topography of the oxidation process and indicate that the oxidation mainly occurs on the topmost layer without altering the chemical composition of underlying layer. The formation of S–O bonds upon short, remote plasma exposure pins the surface Fermi level to the conduction band edge, while the MoO<sub>xsub> formation at high temperature modulates the Fermi level toward the valence band through band alignment. A uniform coverage of monolayer amorphous MoO<sub>3sub> is obtained after 5 min or longer remote O<sub>2sub> plasma exposure at 200 °C, and the MoO<sub>3sub> can be completely removed by annealing at 500 °C, leaving a clean ordered MoS<sub>2sub> lattice structure as verified by XPS, LEED, AFM, and scanning tunneling microscopy. This work shows that a remote O<sub>2sub> plasma can be useful for both surface functionalization and a controlled thinning method for MoS<sub>2sub> device fabrication processes.