单层MoS₂生长机理及光电性能的研究

Study on the Growth Mechanism and Optoelectronic Properties of Monolayer MoS₂

摘要: 本文采用盐辅助化学气相沉积法，以MoO₃、S为前驱体，NaCl为生长促进剂，在SiO₂/Si衬底上成功制备了单层二硫化钼。系统研究了反应物位置、载气流量等工艺参数对MoS₂生长形貌的影响，发现当N₂流量为150 sccm时，可获得尺寸超过50 μm的大面积单层MoS₂三角形岛状结构。通过拉曼光谱、扫描电子显微镜和原子力显微镜对材料质量进行表征，结果表明所制备的MoS₂为单层结构，厚度约0.83 nm，但局部存在由衬底残留物或成核缺陷引起的纳米“帐篷”结构，导致局部应变和双层区域的出现。进一步基于单层MoS₂构筑了光电器件，器件在532 nm激光照射下表现出优异的光电性能：光暗电流比接近10³，响应时间快至微秒级(上升时间12 μs，下降时间85 μs)，响应率最高可达63.4 mA/W。研究表明，盐辅助CVD法生长的单层MoS₂在高速光电探测领域具有良好应用前景。

Abstract: In this paper, monolayer molybdenum disulfide was successfully synthesized on SiO₂/Si substrates via the salt-assisted chemical vapor deposition (CVD) method, using MoO₃ and S as precursors and NaCl as a growth promoter. The effects of process parameters such as reactant position and carrier gas flow rate on the growth morphology of MoS₂ were systematically investigated. It was found that large-area triangular island structures of monolayer MoS₂ with sizes exceeding 50 μm could be obtained at a N₂ flow rate of 150 sccm. The material quality was characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy. The results demonstrate that the as-prepared MoS₂ exhibits a monolayer structure with a thickness of approximately 0.83 nm. However, local nano-“tent” structures induced by substrate residues or nucleation defects exist, leading to local strain and the formation of bilayer regions. Furthermore, optoelectronic devices were constructed based on the monolayer MoS₂, which exhibit excellent photoelectric performance under 532 nm laser irradiation: the photocurrent-to-dark-current ratio is close to 10³, the response time is as fast as the microsecond level (rise time 12 μs, decay time 85 μs), and the maximum responsivity reaches up to 63.4 mA/W. This study suggests that monolayer MoS₂ grown by the salt-assisted CVD method holds promising application prospects in the field of high-speed photodetection.