Xin Xing, Chen Jiamei, Zhang Yanmei, Chen Mao-Lin, Bao Youzhe, Liu Weizhen, Liu Yichun, Xu Haiyang, Ren Wencai
Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Northeast Normal University, Ministry of Education, Changchun 130024, China.
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, Shenyang 110016, P. R. China.
Nanoscale Horiz. 2022 Jun 27;7(7):743-751. doi: 10.1039/d2nh00105e.
The synthesis of large-scale monolayer single-crystal MX (M = Mo, W; X = S, Se), a typical transition metal dichalcogenide (TMD), is the premise for their future applications. Compared with insulating substrates such as SiO and sapphire, Au is more favourable for the fast growth of TMDs by chemical vapor deposition (CVD). Recently, large-scale single-crystal WX was successfully grown and transferred on Au. In sharp contrast, the growth and transfer for monolayer MoX is still very challenging, because Au has a higher solubility of Mo and stronger interaction with MoX than WX. Compared with the most studied MoS, MoSe is superior in many aspects because of the narrower band gap and tunable excitonic charging effects. However, the synthesis of large-scale single-crystal MoSe on Au has not been reported so far. Here, a pre-alloying CVD method was developed to solve the problems for the growth and non-destructive transfer of MoX. It has realized the ultrafast growth (30 s) of submillimeter-scale (560 μm) single-crystal MoSe for the first time. As-grown samples are strictly monolayers with good optical and electrical properties, which can be easily transferred without sacrificing Au foils by the electrochemical bubbling method. It was found that pre-alloying not only passivates the energetically active sites on Au but also weakens the interaction between Au and MoSe, which is responsible for the ultrafast growth and easy transfer of MoSe. This method is also universal for the fast growth and non-destructive transfer of other 2D TMDs.
典型的过渡金属二硫属化物（TMD）——大规模单层单晶MX（M = 钼，钨；X = 硫，硒）的合成是其未来应用的前提。与诸如SiO和蓝宝石等绝缘衬底相比，金更有利于通过化学气相沉积（CVD）实现TMD的快速生长。最近，大规模单晶WX已成功在金上生长并转移。形成鲜明对比的是，单层MoX的生长和转移仍然极具挑战性，因为金对钼的溶解度更高，且与MoX的相互作用比与WX的更强。与研究最多的MoS相比，MoSe在许多方面更具优势，因为其带隙更窄且具有可调谐的激子充电效应。然而，迄今为止尚未报道在金上合成大规模单晶MoSe。在此，开发了一种预合金化CVD方法来解决MoX生长和无损转移的问题。首次实现了亚毫米级（560μm）单晶MoSe的超快生长（30秒）。生长的样品严格为单层，具有良好的光学和电学性质，通过电化学鼓泡法可轻松转移而不牺牲金箔。研究发现，预合金化不仅钝化了金上的高能活性位点，还减弱了金与MoSe之间的相互作用，这是MoSe实现超快生长和易于转移的原因。该方法对于其他二维TMD的快速生长和无损转移同样适用。
