Li Xufan, Kahn Ethan, Chen Gugang, Sang Xiahan, Lei Jincheng, Passarello Donata, Oyedele Akinola D, Zakhidov Dante, Chen Kai-Wen, Chen Yu-Xun, Hsieh Shang-Hsien, Fujisawa Kazunori, Unocic Raymond R, Xiao Kai, Salleo Alberto, Toney Michael F, Chen Chia-Hao, Kaxiras Efthimios, Terrones Mauricio, Yakobson Boris I, Harutyunyan Avetik R
Honda Research Institute USA Inc., San Jose, California 95134, United States.
Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
ACS Nano. 2020 Jun 23;14(6):6570-6581. doi: 10.1021/acsnano.0c00132. Epub 2020 May 1.
The role of additives in facilitating the growth of conventional semiconducting thin films is well-established. Apparently, their presence is also decisive in the growth of two-dimensional transition metal dichalcogenides (TMDs), yet their role remains ambiguous. In this work, we show that the use of sodium bromide enables synthesis of TMD monolayers a surfactant-mediated growth mechanism, without introducing liquefaction of metal oxide precursors. We discovered that sodium ions provided by sodium bromide chemically passivate edges of growing molybdenum disulfide crystals, relaxing in-plane strains to suppress 3D islanding and promote monolayer growth. To exploit this growth model, molybdenum disulfide monolayers were directly grown into desired patterns using predeposited sodium bromide as a removable template. The surfactant-mediated growth not only extends the families of metal oxide precursors but also offers a way for lithography-free patterning of TMD monolayers on various surfaces to facilitate fabrication of atomically thin electronic devices.
添加剂在促进传统半导体薄膜生长方面的作用已得到充分证实。显然，它们的存在对于二维过渡金属二硫属化物（TMD）的生长也起着决定性作用，但其作用仍不明确。在这项工作中，我们表明使用溴化钠能够通过表面活性剂介导的生长机制合成TMD单层，而不会导致金属氧化物前驱体液化。我们发现，溴化钠提供的钠离子对生长中的二硫化钼晶体边缘进行化学钝化，缓解面内应变以抑制三维岛状生长并促进单层生长。为了利用这种生长模式，使用预沉积的溴化钠作为可去除模板，将二硫化钼单层直接生长成所需图案。表面活性剂介导的生长不仅扩展了金属氧化物前驱体的种类，还为在各种表面上对TMD单层进行无光刻图案化提供了一种方法，以促进原子级薄电子器件的制造。
