Control of the Nucleation Density of Molybdenum Disulfide in Large-Scale Synthesis Using Chemical Vapor Deposition

Haitao Xu; Weipeng Zhou; Xiaowu Zheng; Jiayao Huang; Xiliang Feng; Li Ye; Guanjin Xu; Fang Lin

doi:10.3390/ma11060870

Control of the Nucleation Density of Molybdenum Disulfide in Large-Scale Synthesis Using Chemical Vapor Deposition

Materials (Basel). 2018 May 23;11(6):870. doi: 10.3390/ma11060870.

Authors

Haitao Xu¹, Weipeng Zhou², Xiaowu Zheng³, Jiayao Huang⁴, Xiliang Feng⁵, Li Ye⁶, Guanjin Xu⁷, Fang Lin^{8

9}

Affiliations

¹ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. xuhaitao@scau.edu.cn.
² College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. weipengzhou@stu.scau.edu.cn.
³ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. xiaowuzheng@stu.scau.edu.cn.
⁴ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. huangjiayao@casachina.com.cn.
⁵ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. fengxiliang@stu.scau.edu.cn.
⁶ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. yel17@mails.tsinghua.edu.cn.
⁷ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. xuguanjin@stu.scau.edu.cn.
⁸ College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, China. linfang@scau.edu.cn.
⁹ State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China. linfang@scau.edu.cn.

Abstract

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.

Keywords: 2D MoS2 crystal; carrier gas flow rate; chemical vapor deposition; nucleation density.