CVD growth of monolayer MoS2: Role of growth zone configuration and precursors ratio

• Published in: Japanese Journal of Applied Physics 2017-06, Vol.56 (6S1)
• Main Authors: Özden, Ayberk, Ay, Feridun, Sevik, Cem, Perkgöz, Nihan Kosku
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.56.06GG05

Single-layer, large-scale two-dimensional material growth is still a challenge for their wide-range usage. Therefore, we carried out a comprehensive study of monolayer MoS2 growth by CVD investigating the influence of growth zone configuration and precursors ratio. We first compared the two commonly used approaches regarding the relative substrate and precursor positions, namely, horizontal and face-down configurations where face-down approach is found to be more favorable to obtain larger flakes under identical growth conditions. Secondly, we used different types of substrate holders to investigate the influence of the Mo and S vapor confinement on the resulting diffusion environment. We suggest that local changes of the S to Mo vapor ratio in the growth zone is a key factor for the change of shape, size and uniformity of the resulting MoS2 formations, which is also confirmed by performing depositions under different precursor ratios. Therefore, to obtain continuous monolayer films, the S to Mo vapor ratio is needed to be kept within a certain range throughout the substrate. As a conclusion, we obtained monolayer triangles with a side length of 90 µm and circles with a diameter of 500 µm and continuous films with an area of 850 µm × 1 cm when the S-to-Mo vapor ratio is optimized.