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Direct Identification of Surface Bound MoO 3 on Single MoS 2 Flakes Heated in Dry and Humid Air
Author(s) -
Rogala Maciej,
Sokołowski Stanisław,
Ukegbu Ugonna,
Mierzwa Aneta,
Szoszkiewicz Robert
Publication year - 2021
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.202100328
Subject(s) - x ray photoelectron spectroscopy , materials science , relative humidity , atomic force microscopy , analytical chemistry (journal) , spectroscopy , kelvin probe force microscope , nanotechnology , chemical engineering , chemistry , physics , quantum mechanics , engineering , thermodynamics , chromatography
The chemical presence of the MoO x species on single microscopic MoS 2 flakes is shown at two conditions, which are of interest for future MoS 2 ‐based devices and where their presence is not previously confirmed. First, the case of thick MoS 2 flakes oxidatively etched at 350–370 °C in air is treated. Atomic force microscopy (AFM), high resolution X‐ray photoelectron spectroscopy, and X‐ray absorption spectroscopy are combined to unambiguously confirm the chemical presence of the α‐MoO 3 species on such samples, mostly in the form of loose particles. Second, it is shown that MoS 2 flakes heated at temperatures of only 220 °C display a quite uniform ≈2 nm thick MoO x layer at already 10% relative humidity. The presence of such MoO x oxide layers is confirmed by scratching the sample with AFM tips and performing comparative Kelvin probe force microscopy and Auger photoelectron spectroscopy on scratched‐out and untouched parts of the flakes.