Molybdenum disulphide (MoS2) is a layered Van der Waals solid enabling, as in the case of graphene, the isolation of a single MoS2 layer which is essentially a 2D-crystal. Being an indirect-gap (1.3 eV) semiconductor in its bulk form, MoS2 attracted significant attention in the past years when it was found that its 2D counterpart is a direct-gap (~ 1.9 eV) material [1, 2]. Before this material can be properly incorporated into commercial devices, efficient large area growth methods are required.In this work, a two-step atmospheric pressure CVD method is presented, exhibiting controlled and large area growth of single and few-layered 2D-MoS2 crystals through the reaction between sulphur vapours and pre-deposited sodium molybdate (Na2MoO4) on a Si/SiO2 substrate. Depending on the precursor concentration the lateral size of the crystals can be controlled. Moreover, a monotonic increase of the substrate coverage with the precursor concentration is established, which enables the preparation of either isolated monolayers homogeneously distributed on the substrate or continuous MoS2 films with single and few-layer domains. X-ray photoelectron spectroscopy was used to verify the stoichiometry of the produced crystals, while Transmission Electron Microscopy confirmed the high quality of the crystals.
1 Jan 2018
51 st Heyrovský Discussion