収差補正ＴＥＭを用いたナノチューブリアクタにおけるナノ物質生成反応の直接観察

二维金属材料研究的进展在很大程度上依赖于生长技术的发展。到目前为止，对2D金属制备的研究有限，这与2D半导体的情况形成鲜明对比，其中各种层状半导体，包括MoS2，WS2，MoSe2，WSe2，以其单层形式被隔离。在这项工作中，我们已经开发了一种简单的方法来制备二维金属过渡金属二硫属化物（TMDC）的化学气相沉积（CVD）方法，其中直接生长的少层NbS2（3R相）的原子平面六方氮化硼（hBN）已被证明。用原子力显微镜、光学显微镜、电子显微镜和光学光谱对如此生长的NbS2进行结构表征，揭示了利用hBN作为生长衬底是第一次成功CVD生长具有大单畴尺寸（几个m）的2D金属TMDC的关键因素。 电输运测量已经清楚地表明，NbS2原子层低至几层厚度是金属。本研究为二维层状金属材料的可控生长开辟了一条新的合成途径，对于研究二维金属的丰富物理以及寻找新型二维超导体具有重要意义。

Progress on researches of two-dimensional (2D) metals strongly relies on development of the growth technique. Studies on preparation of 2D metals have so far been limited, and this is in stark contrast to the situation of 2D semiconductors, where various layered semiconductors, including MoS2, WS2, MoSe2, WSe2, have been isolated in its monolayer form. In this work, we have developed a facile method to prepare 2D metallic transition metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD) method, where direct growth of few-layered NbS2 (3R phase) on atomically flat hexagonal boron nitride (hBN) has been demonstrated. Structural characterization of the so-grown NbS2 was performed with atomic force microscopy, optical microscopy, electron microscopy and optical spectroscopy, revealing that the utilization of hBN as growth substrates is a key factor for the first successful CVD growth of 2D metallic TMDCs with large single-domain size (several µm). Electrical transport measurements have clearly shown that NbS2 atomic layers down to few-layer-thickness are metal. The current study opens up a new synthetic route for controllable growth of 2D layered metallic materials, which is of great importance in study of rich physics in 2D metals, as well as in search for novel 2D superconductors.