In situ X-ray photoelectron spectroscopy study: effect of inert Ar sputter etching on the core-level spectra of the CVD-grown tri-layer MoS2 thin films

• Published in: Journal of materials science. Materials in electronics Vol. 33; no. 11; pp. 8741 - 8746
• Main Authors: Jayaseelan, V., Kalaiezhily, R. K., Shinde, Nitin Babu, Kamala Bharathi, K., Navaneethan, M., Eswaran, Senthil Kumar
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2022; Springer Nature B.V
• Subjects: Argon; Characterization and Evaluation of Materials; Chemical vapor deposition; Chemistry and Materials Science; Electronic devices; Etching; Excitons; Ions; Materials Science; Molybdenum; Molybdenum disulfide; Molybdenum oxides; Optical and Electronic Materials; Oxidation; Photoelectrons; Photoluminescence; Raman spectroscopy; Sapphire; Spectrum analysis; Thin films; Valence; X ray photoelectron spectroscopy
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-06798-2

Atomically thin molybdenum disulfide (MoS 2 ) thin films are a promising avenue of investigation due to its potential applications in modern nanoscale electronic devices. In this work, we present a systematic investigation of the effect of in situ argon-ion sputter etching on the core-level X-ray photoelectron spectroscopy (XPS) of the chemical vapor-deposited MoS 2 thin films. Raman spectroscopy of the MoS 2 reveals that the thin films are tri-layer samples. Photoluminescence spectrum of the tri-layer MoS 2 consists of A- and B-exciton emission peaks at 1.85 and 1.99 eV, respectively. The core-level XPS spectra of the Mo-3d and S-2p levels of the tri-layer MoS 2 were investigated for various in situ sputter etch time. The as-grown and 6 s sputter-etched MoS 2 sample exhibited Mo-3d spin–orbit doublets corresponding to + 4 oxidation state of Mo. For the sputter etch time beyond 40 s, the sample exhibited + 6 oxidation states of molybdenum suggesting the presence of thin molybdenum oxide at the interface between MoS 2 and sapphire. We have also observed mid oxidation states like Mo 5+ , which is attributed to the argon-ion sputter etch-induced sulfur-deficient mixed S–Mo–O and sub-stoichiometric phases.