Minor structural changes in transition metal dichalcogenides can have dramatic effects on their electronic properties. This makes the quest for key parameters that enable a selective choice between the competing metallic and semiconducting phases in the 2D MoTe₂ system compelling. Herein, we report the optimal conditions at which the choice of the initial seed layer dictates the type of crystal structure of atomically-thin MoTe₂ films grown by chemical vapour deposition (CVD). When Mo metal is used as a seed layer, semiconducting 2H-MoTe₂ is the only product. Conversely, MoO₃ leads to the preferential growth of metallic 1T′-MoTe₂. The control over phase growth allows for simultaneous deposition of both 2H-MoTe₂ and 1T′-MoTe₂ phases on a single substrate during one CVD reaction. Furthermore, Rhodamine 6G dye can be detected using few-layered 1T′-MoTe₂ films down to 5 nM concentration, demonstrating surface enhanced Raman spectroscopy (SERS) with sensitivity several orders of magnitude higher than for bulk 1T′-MoTe₂.

过渡金属二卤化碳的微小结构变化对其电子性能会产生巨大影响。这就要求在2D MoTe ₂系统中能够在竞争的金属相和半导体相之间进行选择的关键参数。本文中，我们报告了最佳条件，在该条件下，初始种子层的选择将决定通过化学气相沉积（CVD）生长的原子级薄MoTe ₂薄膜的晶体结构类型。当Mo金属用作籽晶层时，半导体2H-MoTe ₂是唯一的产品。相反，MoO ₃导致金属1T'-MoTe ₂优先生长。对相生长的控制允许在一个CVD反应期间在单个衬底上同时沉积2H-MoTe ₂和1T'-MoTe ₂相。此外，若使用低至5 nM浓度的几层1T'-MoTe ₂膜，可检测罗丹明6G染料，这表明表面增强拉曼光谱（SERS）的灵敏度比本体1T'-MoTe ₂高出几个数量级。