Ma Zongpeng, Wang Shiyao, Deng Qixin, Hou Zhufeng, Zhou Xing, Li Xiaobo, Cui Fangfang, Si Huayan, Zhai Tianyou, Xu Hua
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.
Small. 2020 Apr;16(16):e2000596. doi: 10.1002/smll.202000596. Epub 2020 Mar 12.
Research on transition metal dichalcogenides (TMDs) has been accelerated by the development of large-scale synthesis based on chemical vapor deposition (CVD) growth. However, in most cases, CVD-grown TMDs are composed of randomly oriented grains, and thus contain many distorted grain boundaries (GBs), which seriously degrade their electrical and photoelectrical properties. Here, the epitaxial growth of highly aligned MoS grains is reported on a twofold symmetry a-plane sapphire substrate. The obtained MoS grains have an unusual rectangle shape with perfect orientation alignment along the [1-100] crystallographic direction of a-plane sapphire. It is found that the growth temperature plays a key role in its orientation alignment and morphology evolution, and high temperature is beneficial to the initial MoS seeds rotate to the favorable orientation configurations. In addition, the photoluminescence quenching of the well-aligned MoS grains indicates a strong MoS -substrate interaction which induces the anisotropic growth of MoS , and thus brings the formation of rectangle shape grains. Moreover, the well-aligned MoS grains splice together without GB formation, and thus that has negligible effect on its electrical transport properties. The progress achieved in this work could promote the controlled synthesis of large-area TMDs single crystal film and the scalable fabrication of high-performance electronic devices.
基于化学气相沉积（CVD）生长的大规模合成技术的发展加速了对过渡金属二硫属化物（TMDs）的研究。然而，在大多数情况下，CVD生长的TMDs由随机取向的晶粒组成，因此包含许多扭曲的晶界（GBs），这严重降低了它们的电学和光电性能。在此，报道了在具有双重对称性的a面蓝宝石衬底上高度取向排列的MoS晶粒的外延生长。所获得的MoS晶粒具有不寻常的矩形形状，沿a面蓝宝石的[1-100]晶向具有完美的取向排列。发现生长温度在其取向排列和形貌演变中起关键作用，高温有利于初始MoS籽晶旋转到有利的取向构型。此外，排列良好的MoS晶粒的光致发光猝灭表明存在强烈的MoS-衬底相互作用，这诱导了MoS的各向异性生长，从而导致矩形晶粒的形成。而且，排列良好的MoS晶粒拼接在一起而不形成晶界，因此对其电输运性能的影响可忽略不计。这项工作所取得的进展可以促进大面积TMDs单晶膜的可控合成以及高性能电子器件的可扩展制造。
