Controlled Growth and Properties Modulation of Two-Dimensional Transition Metal Dichalcogenides

可控生长和性能调控二维过渡金属硫族化合物

王经纬

11651003

博士

纳米科学与技术

程春

2020-02-02

2020-02-02

香港科技大学

香港

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted great research interests due to their potential applications in electronics, photonics, optoelectronics, etc. Chemical vapor deposition (CVD) technique is believed to be the most promising method to realize the batch production of high-quality 2D TMDCs. However, precise control of TMDCs’ growth and properties by the CVD method is still a challenge. In this thesis, several strategies are provided for manipulating the CVD growth process and engineering the structures of 2D TMDCs. Firstly, the monolayer MoS2 with pointed star-like morphologies have been successfully prepared via the CVD method. Theoretical calculations imply the defects density is closely related to the sample morphology. By pretreating the growth substrate with adhesive seeds, the dendritic MoS2 with hexagonal backbones have been controllably synthesized. These MoS2 dendrites consist of massive twin defects which greatly enhance the photoluminescence (PL) emission. Moreover, by using the m-plane single-crystal quartz as the growth substrate, aligned growth of monolayer WS2 together with the engineered band structure and dimension have been achieved. A direct-indirect bandgap transition of monolayer WS2 occurs when the substrate is cooled down to the low temperature. By controlling the growth time, the dimension of epitaxial WS2 can be tailored from the 2D triangle to the one-dimensional ribbon. Finally, wrinkled WS2 arrays have been directly prepared on m-plain quartz by a simple post-quenching process. These nanoscale WS2 wrinkles exhibit anisotropic Raman response, patterned PL emission, and enhanced chemical reactivity.

二维（2D）过渡金属硫族化合物（TMDCs）在电子、光子学、光电子等领域有着广泛的应用前景，化学气相沉积（CVD）技术被认为是实现高质量2D-tmdc批量生产的最有前途的方法。然而，用CVD法精确控制tmdc的生长和性能仍然是一个挑战。在这篇论文中，我们提供了一些策略来控制CVD生长过程和设计二维TMDC的结构。首先，采用化学气相沉积法成功地制备了具有尖角星状形貌的单层MoS2。理论计算表明，缺陷密度与样品形貌密切相关。通过对生长基片进行预处理，制备出具有六角骨架的树枝状MoS2。这些MoS2枝晶由大量孪晶缺陷组成，极大地增强了光致发光（PL）发射。此外，以m面单晶石英为生长基质，实现了WS2单层膜的定向生长以及工程化的能带结构和尺寸。当衬底冷却到低温时，单层WS2发生直接间接带隙跃迁。通过控制生长时间，可以将外延WS2的尺寸从二维三角形调整到一维带状。最后，通过简单的后淬火工艺，在m-平面石英表面直接制备了褶皱WS2阵列。这些纳米尺度的WS2褶皱显示出各向异性的拉曼响应、图案化的PL发射和增强的化学反应性。

2D materials chemical vapor deposition MoS2 WS2

英语

联合培养

南方科技大学

Wang JW. Controlled Growth and Properties Modulation of Two-Dimensional Transition Metal Dichalcogenides[D]. 香港. 香港科技大学,2020.