Chemical vapor deposition (CVD) of two-dimensional (2D) materials such as monolayer MoS2 typically involves the conversion of vapor-phase precursors to a solid product in a process that may be described as a vapor-solid-solid (VSS) mode. Here, we report the first demonstration of vapor-liquid-solid (VLS) growth of monolayer MoS2 yielding highly crystalline ribbon-shaped structures with a width of a few tens of nanometers to a few micrometers. The VLS growth mode is triggered by the reaction between molybdenum oxide and sodium chloride, which results in the formation of molten Na-Mo-O droplets. These droplets mediate the growth of MoS2 ribbons in the "crawling mode" when saturated with sulfur on a crystalline substrate. Our growth yields straight and kinked ribbons with a locally well-defined orientation, reflecting the regular horizontal motion of the liquid droplets during growth. Using atomic-resolution scanning transmission electron microscopy (STEM) and second harmonic generation (SHG) microscopy, we show that the ribbons are homoepitaxially on monolayer MoS2 surface with predominantly 2H- or 3R-type stacking. These findings pave the way to novel devices with structures of mixed dimensionalities.
@article{arxiv.1801.09043,
title = {Vapor-Liquid-Solid Growth of Monolayer MoS2 Nanoribbons},
author = {Shisheng Li and Yung-Chang Lin and Wen Zhao and Jing Wu and Zhuo Wang and Zehua Hu and Youde Shen and Dai-Ming Tang and Junyong Wang and Qi Zhang and Hai Zhu and Leiqiang Chu and Weijie Zhao and Chang Liu and Zhipei Sun and Takaaki Taniguchi and Minoru Osada and Wei Chen and Qing-Hua Xu and Andrew Thye Shen Wee and Kazu Suenaga Feng Ding and Goki Eda},
journal= {arXiv preprint arXiv:1801.09043},
year = {2018}
}