Chemical Vapor Deposition Growth of Few-Layer MoTe₂ in the 2H, 1T′, and 1T Phases: Tunable Properties of MoTe₂ Films

Chemical vapor deposition allows the preparation of few-layer films of MoTe₂ in three distinct structural phases depending on the growth quench temperature: 2H, 1T′, and 1T. We present experimental and computed Raman spectra for each of the phases and utilize transport measurements to explore the properties of the 1T MoTe₂ phase. Density functional theory modeling predicts a (semi-)­metallic character. Our experimental 1T films affirm the former, show facile μA-scale source-drain currents, and increase in conductivity with temperature, different from the 1T′ phase. Variation of the growth method allows the formation of hybrid films of mixed phases that exhibit susceptibility to gating and significantly increased conductivity

Gold Dispersion and Activation on the Basal Plane of Single-Layer MoS₂

Gold islands are typically associated with high binding affinity to adsorbates and catalytic activity. Here we present the growth of dispersed nanoscale gold islands on single layer MoS₂, prepared on an inert SiO₂/Si support by chemical vapor deposition. This study offers a combination of growth process development, optical characterization, photoelectron spectroscopy at submicron spatial resolution, and advanced density functional theory modeling for detailed insight into the electronic interaction between gold and single-layer MoS₂. In particular, we find the gold density of states in Au/MoS₂/SiO₂/Si to be far less well-defined than Au islands on other 2-dimensional materials such as graphene, for which we also provide data. We attribute this effect to the presence of heterogeneous Au adatom/MoS₂-support interactions within the nanometer-scale gold cluster. Theory predicts that CO will exhibit adsorption energies in excess of 1 eV at the Au cluster edges, where the local density of states is dominated by Au 5d_<i>z</i>2 symmetry