精确控制成核点位置是制备高质量二维纳米材料的关键.通过旋涂氧化石墨烯(GO)水溶液,在衬底上分散GO纳米片作为促成核种子层,成功制备了MoS2二维纳米片.MoS2纳米片的拉曼光谱峰位差(A1g-E12g)为19.5 cm-1,其表面与衬底表面的高度差为o.85 nm,说明所生长的MoS2纳米片为单原子层结构.扫描电镜观察到,成核有两种方式,分别是以GO纳米片成核和GO富集MoS2分子成核.两种方式均有助于水平生长单层的MoS2纳米片.

Atmospheric pressure chemical vapor deposition (CVD) is presently a promising approach for preparing two-dimensional (2D) MoS2 crystals at high temperatures on SiO2/Si substrates. In this work, we propose an improved CVD method without hydrogen, which can increase formula flexibility by controlling the heating temperature of MoO3 powder and sulfur powder. The results show that the size and coverage of MoS2 domains vary largely, from discrete triangles to continuous film, on substrate. We find that the formation of MoS2 domains is dependent on the nucleation density of MoS2. Laminar flow theory is employed to elucidate the cause of the different shapes of MoS2 domains. The distribution of carrier gas speeds at the substrate surface leads to a change of nucleation density and a variation of domain morphology. Thus, nucleation density and domain morphology can be actively controlled by adjusting the carrier gas flow rate in the experimental system. These results are of significance for understanding the growth regulation of 2D MoS2 crystals.

本文基于CVD系统,提出了采用衬底正置法的单层二硫化钼二维晶体的合成方法,对制备单层二硫化钼二维晶体的生长条件进行探究,并对样品的生长机制进行归纳和总结.若干表征技术的反馈结果表明,采用此方法制备的硫化钼二维晶体具备较高的晶体质量,样品生长在载气空间分布方向上存在最佳位置.