大尺寸过渡金属二硫化合物异质结的制备及其光电性能的研究

The advancement of transition metal dichalcogenides (TMDCs）requires profound knowledges on the performance and optimization mechanism of their heterostructures. Therefore, the proposed work aims to seek a proper way to synthesize large-scale TMDCs vertical heterostructures and engineer them for better uses. To this end, the properties of heterostructures need to be tuned via elemental doping in individual layer, applying B-field or E-field, and absorption to modify their electronic structure and carrier transfer behaviors which serve as to improve the performance of devices based on these TMDCs heterostructures. Combined with first-principles calculations, the physical insights of these changes will be explored. The correlation between doping and electronic states (including spin states, magnetic behaviors) will be investigated. Their interfacial electronic interaction will also be linked to the modification of individual layer, which affects charge transfer between the layers. Above-mentioned information is in great need for optoelectronic and photocatalytic fields, which is heavily affected by carrier transfer properties. In addition, the roles of surface crystal field on photocatalytic performance will be studied thoroughly to pursue optimized ways for electronic engineering in order to enhance their photocatalytic performance of TMDCs heterostructures. The proposed studies are conducted to promote potential applications of TMDCs in optoelectronic and photocatalytic areas.

过渡金属二硫化物（TMDCs）的进一步发展迫切需要对其二维异质结特性及性能优化机理进行深入研究。为此，本项目将展开大尺寸TMDCs二维垂直异质结的制备和研究，通过层内掺杂及磁、电、外力、表面吸附等外来因素实现对异质结界面电子特性的控制，优化其电子结构及载流子传输特性，为其器件功能放大化提供保障。为揭示其物理机制，该项目将结合第一性原理计算，研究层内掺杂对电子态（包括自旋态、磁性）的调控机理，阐明层内改性对界面电子相互作用的影响。通过设计层间物理结构实现电荷的定向转移，调节其光电、光敏特性，搭建载流子输运与光催化特性之间的桥梁。另外，本研究将通过表面晶体场的修饰实现对异质结界面光生载流子输运的调制。本项目旨在提升TMDCs二维异质结的应用前景，为光电、光催化领域作出重要贡献。

过渡金属二硫化物（TMDCs）的进一步发展迫切需要对其二维异质结特性及性能优化机理进行深入研究。为此，本项目开展了TMDCs二维异质结的制备和研究，对气相-液相-固相（VLS）的生长机制给出了新的诠释。之前研究认为，化学气相沉积(CVD)生长MoS2可以通过VLS生长机制形成，依赖于表面扩散引导Na-Mo-O液滴的运动。在此之上，我们研究了在表面扩散受到抑制的情况下，单分子层二硫化钼可以通过Na-Mo-O液滴的再蒸发而向内生长。在这个再气化过程中，在液滴表面形成的生长核，被下面的蒸气推开，直到最后一层原子的蒸气压降至零，这就保证了更容易形成大尺寸单层膜。制备的MoS2单层膜具有与传统CVD方法相同的晶体质量。随着对不同衬底上VLS生长过程理解的不断深入，使我们能够更好地控制各种纳米电子器件上原子薄膜MoS2的制备。此外，项目研究了WS2/MoS2异质结制备过程中特殊形貌的形成机理。为揭示其物理机制，该项目结合了蒙特卡洛模拟计算，从原子层面上研究异质结的生长动力学及TMDCs的热解吸附原理，阐述了不同生长形貌的WS2/MoS2异质结形成的动力学原因。项目研究了MoS2与其他功能材料形成的异质结复合材料的光电性能。通过异质结的设计优化了界面电子结构及载流子传输特性。研究外来因素（比如Au吸附）对异质结界面电荷转移的影响，建立了能促进异质结器件电子特性和推动光电响应的优化方案。为该材料体系在光电、光催化领域的实际应用做出了一定贡献。