Large-Area and High-Quality 2D Transition Metal Telluride

Large-scale and atom-thin ditellurides including WTe₂ and MoTe₂ were synthesized. The Te powder was used as the Te sources. The crystals were synthesized in quartz tube with temperature from 700 to 850°C. Specifically, for the WTe₂, the mixed gas of H2/Ar with 15 and 150 sccm was used as the carrier gas, the silicon boat containing 30 mg mixed powders with WO₃:WCl₆:Te =1:1:1(weight ratio) was put in the center of the tube. The SiO₂/Si substrate was placed downstream. Another silicon boat containing 0.5 g Te powder was put on the upstream. The temperature ramped up to the 780°C in 16 min, and kept at the reaction temperature for about 5 to 15 min. Then, the furnace cooled down to room temperature gradually. Raman spectroscopy was employed to characterize the quality of the WTe₂ and MoTe₂ atomic layers. The result shows the Raman spectra of WTe₂ films with different thicknesses ranging from monolayer to bulk. The as-synthesized MoTe₂ atomic layer also maintains the 1T₂ phase similar to the WTe₂ in the monolayer form presented above, while structural difference can be observed in the few layer flakes due to the different interlayer stacking structure.