Large-scale integration of MoS2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor-solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS2 films onto SiO2/Si substrates with a tunable thickness and cm(2)-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS2 layers is dictated by the deposition temperature and thickness. In particular, the MoS2 structural disorder observed at low temperature (<750 °C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 °C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after sulfurization, this parametrical dependence is associated with the inherent granularity of the MoS2 nanosheet that is inherited by the pristine morphology of the pre-deposited Mo film. This work paves the way to a closer control of the synthesis of wafer-scale and atomically thin MoS2, potentially extendable to other transition metal dichalcogenides and hence targeting massive and high-volume production for electronic device manufacturing.

The structural defects in two-dimensional transition metal dichalcogenides, including point defects, dislocations and grain boundaries, are scarcely considered regarding their potential to manipulate the electrical and optical properties of this class of materials, notwithstanding the significant advances already made. Indeed, impurities and vacancies may influence the exciton population, create disorder-induced localization, as well as modify the electrical behaviour of the material. Here we report on the experimental evidence, confirmed by ab initio calculations, that sulfur vacancies give rise to a novel near-infrared emission peak around 0.75 eV in exfoliated MoS2 flakes. In addition, we demonstrate an excess of sulfur vacancies at the flake's edges by means of cathodoluminescence mapping, aberration-corrected transmission electron microscopy imaging and electron energy loss analyses. Moreover, we show that ripplocations, extended line defects peculiar to this material, broaden and redshift the MoS2 indirect bandgap emission.

Highly oriented antimony telluride thin films are prepared by room temperature metalorganic chemical vapor deposition on Si(111).

The growth of atomically thin MoS2 films is achieved by sulfurization of molybdenum oxide precursor films grown by atomic layer deposition. The quality features of the MoS2 films are engineered controlling the stoichiometry, morphology, and thickness of the precursors. The interface interaction between the precursor films and the substrates (SiO2 or sapphire) plays a key role in the MoS2 formation.

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. The thermal conductivity of Ge 2 Sb 2 Te 5 ͑GST͒ layers, as well as the thermal boundary resistance at the interface between the GST and amorphous SiO 2 , was measured using a photothermal radiometry experiment. The two phase changes in the Ge 2 Sb 2 Te 5 were retrieved, starting from the amorphous and sweeping to the face centered cubic ͑fcc͒ crystalline state at 130°C and then to the hexagonal crystalline phase ͑hcp͒ at 310°C. The thermal conductivity resulted to be constant in the amorphous phase, whereas it evolved between the two crystalline states. The thermal boundary resistance at the GST-SiO 2 interface was estimated to be higher for the hcp phase than for the amorphous and fcc ones.