A Simple Method for Synthesis of High-Quality Millimeter-Scale 1T' Transition-Metal Telluride and Near-Field Nanooptical Properties.

The controlled synthesis of MoTe2 and WTe2 is crucial for their fundamental research and potential electronic applications. Here, a simplified ambient-pressure chemical vapor deposition (CVD) strategy is developed to synthesize high-quality and large-scale monolayer and few-layer 1T'-phase MoTe2 (length ≈ 1 mm) and WTe2 (length ≈ 350 µm) crystals by using ordinary salts (KCl or NaCl) as the growth promoter combining with low-cost (NH4 )6 Mo7 O24 ·4H2 O and hydrate (NH4 )10 W12 O41 ·xH2 O as the Mo and W sources, respectively. Atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy confirm the high-quality nature and the atomic structure of the as-grown 1T' MoTe2 and WTe2 flakes. Variable-temperature transport measurements exhibit their semimetal properties. Furthermore, near-field nanooptical imaging studies are performed on the 1T' MoTe2 and WTe2 flakes for the first time. The sub-wavelength effects of 1T'-phase MoTe2 (λp ≈ 140 nm) and WTe2 (λp ≈ 100 nm) are obtained. This approach paves the way for the growth of special transition-metal dichalcogenides materials and boosts the future polaritonic research of 2D telluride compounds.