The chemical interaction of Mn with the MoS2(0001) surface studied by high-resolution photoelectron spectroscopy

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Abstract
The interface produced by vapor deposition of Mn on the MoS2(0001) surface has been studied in situ by high-resolution photoelectron spectroscopy using synchrotron radiation. The evolution of the Mo 3d, Mn 3p, and S 2p core levels and of the valence-band spectra during growth of thin films (10–58 Å) is consistent with partial conversion of the Mn overlayer to MnS via the overall reaction 2Mn+MoS2→2MnS+Mo. The persistence of the substrate components of the Mo 3d and S 2p spectra for thicknesses >35 Å are consistent with the Volmer–Weber growth mode. Annealing a 58-Å film to 770 K resulted in an overlayer film consisting mostly of MnS coexisting with some metallic Mn. Analysis of the Mo 3d core levels indicates the production of a MoS2(0001) surface with S vacancy defects. Annealing to temperatures between 850 and 1040 K drove the reaction to completion (as shown by the valence band and Mn 3p core level spectra). Annealing of the sample to 1130 K resulted in uncovering the MoS2(0001) surface due to breakup of the reacted layer. In addition, low-energy electron diffraction indicated the formation of (0001)–2×2 regions on the surface. This surface structure is interpreted in terms of an ordered, MoS2−x sulfur vacancy defect structure rather than a Mn–Mo–S compound.