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)₆Mo₇O₂₄·4H₂O and hydrate (NH₄)₁₀W₁₂O₄₁·xH₂O 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 (λ_p ≈ 140 nm) and WTe₂ (λ_p ≈ 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.

High-quality and millimeter-scale two-dimensional (2D) 1T′-phase MoTe₂ and WTe₂ crystals are synthesized through a simplified chemical vapor deposition (CVD) strategy by using green and ordinary salt as a promoter. Near-field nanooptical studies are performed on the as-grown 1T′ transition-metal tellurides for the first time. The sub-wavelength effects of 1T′-phase MoTe₂ (λ_p ≈ 140 nm) and WTe₂ (λ_p ≈ 100 nm) are obtained.

http://ift.tt/2xkmW2e