Center for Nanochemistry (CNC), Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China.
Chem Soc Rev. 2015 May 7;44(9):2587-602. doi: 10.1039/c4cs00258j. Epub 2014 Sep 26.
As structural analogues of graphene but with a sizeable band gap, monolayers of group-VIB transition metal dichalcogenides (MX2, M = Mo, W; X = S, Se, Te, etc.) have emerged as the ideal two dimensional prototype for exploring fundamental issues in physics such as valley polarization, and for engineering a wide range of nanoelectronic, optoelectronic and photocatalytic applications. Recently, chemical vapour deposition (CVD) was introduced as a more efficient preparation method than traditional chemical or physical exfoliation options, and has allowed for the successful synthesis of large-area MX2 monolayers possessing a large domain size, high thickness uniformity and continuity, and satisfactory crystal quality. This tutorial review therefore focuses on introducing the more recent advances in the CVD growth of MX2 (MoS2, WS2, MoS2(1-x)Se2xetc.) monolayers via the sulphurisation/decomposition of pre-deposited metal-based precursors, or the one-step reaction and deposition of gaseous metal and chalcogen feedstocks. Differences in growth behaviour caused by commonly used amorphous SiO2/Si, and newly adopted insulating single crystal substrates such as sapphire, mica and SrTiO3, are also comparatively presented. Also discussed are the essential parameters that influence the growth of MX2, such as the temperature, the source-substrate distance and the composition of the carrier gas (Ar/H2). Finally, an assessment is provided for viable future pathways for fine-tuning of the domain size and orientation, thickness uniformity, and the bandgap of MX2 and its alloys.
作为石墨烯的结构类似物，但具有相当大的带隙，单层 VIB 族过渡金属二卤化物（MX2，M = Mo，W；X = S，Se，Te 等）已成为探索物理基本问题的理想二维原型，例如谷极化，并可用于工程各种纳米电子、光电和光催化应用。最近，化学气相沉积（CVD）作为一种比传统化学或物理剥落方法更有效的制备方法被引入，并且已经成功地合成了具有大面积、高厚度均匀性和连续性以及令人满意的晶体质量的 MX2 单层。因此，本教程综述重点介绍了通过预先沉积的金属基前体的硫化/分解，或者气态金属和硫属元素进料的一步反应和沉积，通过 CVD 生长 MX2（MoS2、WS2、MoS2（1-x）Se2x 等）单层的最新进展。还比较了常用的非晶态 SiO2/Si 和新采用的绝缘单晶衬底（如蓝宝石、云母和 SrTiO3）引起的生长行为差异。还讨论了影响 MX2 生长的重要参数，如温度、源-衬底距离和载气（Ar/H2）的组成。最后，对微调 MX2 及其合金的畴大小和取向、厚度均匀性和带隙的可行未来途径进行了评估。
