Surface Characterization of MoS Atomic Layers Mechanically Exfoliated on a Si Substrate.

Mo disulfide overlayers with the thickness exceeding 1.77 nm were obtained on Si substrates through mechanical exfoliation. The resulting Mo disulfide flakes were then analyzed ex situ using combination of Auger electron spectroscopy (AES), elastic-peak electron spectroscopy (EPES) and scanning electron microscopy (SEM) in order to characterize their surface chemical composition, electron transport phenomena and surface morphology.

Determination of surface composition by X-ray photoelectron spectroscopy taking into account elastic photoelectron collisions.

It is now well known that elastic photoelectron scattering in the surface region of solids cannot be ignored in the mathematical formalism of quantitative XPS. Elastic collisions may increase or decrease the photoelectron signal intensity, depending on the experimental configuration. Consequently, it is advisable to take into account these effects in calculations of the surface composition.

Inelastic mean free path data for Si corrected for surface excitation.

Surface-sensitive electron spectroscopies, like Auger electron spectroscopy, X-ray photoelectron spectroscopy and elastic peak electron spectroscopy (EPES) are suitable techniques to investigate surfaces and thin layers. A theoretical model for electron transport is needed to process the observed electron spectra. Electron transport descriptions are based on the differential elastic cross sections for the sample atoms and the inelastic mean free path (IMFP) of backscattered electrons.