Operando Study of Thermal Oxidation of Monolayer MoS2

Sangwook Park; Angel T Garcia-Esparza; Hadi Abroshan; Baxter Abraham; John Vinson; Alessandro Gallo; Dennis Nordlund; Joonsuk Park; Taeho Roy Kim; Lauren Vallez; Roberto Alonso-Mori; Dimosthenis Sokaras; Xiaolin Zheng

doi:10.1002/advs.202002768

Operando Study of Thermal Oxidation of Monolayer MoS₂

Adv Sci (Weinh). 2021 Mar 1;8(9):2002768. doi: 10.1002/advs.202002768. eCollection 2021 May.

Authors

Sangwook Park^{1

2}, Angel T Garcia-Esparza^{1

3}, Hadi Abroshan^{4

5}, Baxter Abraham^{3

6}, John Vinson⁷, Alessandro Gallo⁴, Dennis Nordlund³, Joonsuk Park⁸, Taeho Roy Kim⁹, Lauren Vallez¹, Roberto Alonso-Mori⁶, Dimosthenis Sokaras³, Xiaolin Zheng¹

Affiliations

¹ Department of Mechanical Engineering Stanford University Stanford CA 94305 USA.
² Department of Mechanical Engineering Seoul National University Seoul 08826 South Korea.
³ Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA.
⁴ SUNCAT Center for Interface Science and Catalysis SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA.
⁵ School of Chemistry and Biochemistry Georgia Institute of Technology Atlanta GA 30332 USA.
⁶ Linac Coherent Light Source SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA.
⁷ National Institute of Standards and Technology 100 Bureau Drive Gaithersburg MD 20899 USA.
⁸ Materials Science and Engineering Stanford University Stanford CA 94305 USA.
⁹ Stanford Nano Shared Facilities Stanford University Stanford CA 94305 USA.

Abstract

Monolayer MoS₂ is a promising semiconductor to overcome the physical dimension limits of microelectronic devices. Understanding the thermochemical stability of MoS₂ is essential since these devices generate heat and are susceptible to oxidative environments. Herein, the promoting effect of molybdenum oxides (MoO _x ) particles on the thermal oxidation of MoS₂ monolayers is shown by employing operando X-ray absorption spectroscopy, ex situ scanning electron microscopy and X-ray photoelectron spectroscopy. The study demonstrates that chemical vapor deposition-grown MoS₂ monolayers contain intrinsic MoO _x and are quickly oxidized at 100 °C (3 vol% O₂/He), in contrast to previously reported oxidation thresholds (e.g., 250 °C, t ≤ 1 h in the air). Otherwise, removing MoO _x increases the thermal oxidation onset temperature of monolayer MoS₂ to 300 °C. These results indicate that MoO _x promote oxidation. An oxide-free lattice is critical to the long-term stability of monolayer MoS₂ in state-of-the-art 2D electronic, optical, and catalytic applications.

Keywords: 2D materials; monolayer molybdenum disulfide; operando oxidation; thermochemistry.