Ion-mediated growth of ultra thin molybdenum disulfide layers on highly oriented pyrolytic graphite
Ion-mediated growth of ultra thin molybdenum disulfide layers on highly oriented pyrolytic graphite
复制标题
DOI：
10.1016/j.surfcoat.2018.05.031
复制
发表时间：
2018-09
影响因子：
5.4
通讯作者：
Erik Pollmann;P. Ernst;L. Madauß;M. Schleberger
中科院分区：
文献类型：
--
作者：
Erik Pollmann;P. Ernst;L. Madauß;M. Schleberger
由不同二维（2D）材料组成的范德华（vdW）异质结构是许多新型器件的核心。化学气相沉积（CVD）可以将二维材料直接生长在彼此的顶部，从而以自下而上的方式构建vdW异质结构，从而制备出质量最高且适合应用的vdW异质结构。然而，通过精确控制其生长来获得均匀质量的层是一个严峻的挑战。我们工作的目的是了解生长机制，我们选择了高取向热解石墨（HOPG）上的mos2层作为mos2 -石墨烯界面的模型系统。在我们的模型系统中，我们观察到mos2层不是生长在HOPG阶地上，而是更有可能生长在HOPG边缘，一维缺陷，这显然是生长的种子。然而，在石墨烯中，阶梯边缘是不存在的，而且商业上可用的CVD石墨烯的质量不断提高，每单位面积的缺陷越来越少。虽然这对大多数器件来说显然是一个优势，但根据我们的发现，它构成了自下而上制备vdW异质结构的主要缺点。为了克服这一障碍，我们通过高电荷离子辐照人为地在HOPG表面引入缺陷。通过这种方法，我们可以在化学气相沉积mos2之前诱导出易于控制的准零维缺陷数量。我们发现，这种处理导致了HOPG梯田顶部mos2岛的生长。
Van der Waals (vdW) heterostructures composed of different two-dimensional (2D) materials are at the center of many novel devices. To prepare vdW heterostructures which are of the highest quality and suitable for applications, chemical vapour deposition (CVD) can be used to grow the 2D materials directly on top of each other and thus build the vdW heterostructure in a bottom-up fashion. However, obtaining layers of uniform quality by precisely controlling their growth poses a severe challenge. The aim of our work is to understand the growth mechanisms and we have chosen MoS2layers on highly oriented pyrolytic graphite (HOPG) as a model system for the MoS2-graphene interface. In our model system we observe, that MoS2layers do not grow on the HOPG terraces but are more likely to grow at HOPG edges, one-dimensional defects, which obviously acts as growth seeds. In graphene however, step edges are absent and the ever-improving quality of commercially available CVD graphene yields less and less defects per unit area. While this is clearly an advantage for most devices, in the light of our findings it constitutes a major disadvantage for the bottom-up preparation of vdW heterostructures. To overcome this obstacle we artificially introduce defects into the HOPG surface by highly charged ion irradiation. In this way we induce an easily controllable number of quasi zero-dimensional defects before the chemical vapour deposition of MoS2takes place. We show that this treatment results in MoS2island growth on top HOPG terraces.