二维纳米材料范德华异质结构接触界面处电荷转移及激子态调控

半导体异质结构激子态行为，包括激子的产生、转移、分离及复合等，对于深入探索新的物理机制及开发高效的光电器件具有重要的指导意义。相比于传统的半导体异质结构，范德华异质结构界面处无悬键，并且不存在界面匹配问题，是异质结构激子态行为研究的理想体系。本项目以TMDs/石墨烯范德华异质结构作为研究对象，利用电化学电解质调节石墨烯的费米能级，进而改变异质结构之间界面处能带排列及层间耦合行为，并利用光致发光光谱及瞬态吸收光谱分别研究层间耦合作用对TMDs/石墨烯中激子态行为(激子类型、激子结合能及强度等)与激子态电荷转移动力学的影响；利用扫描隧道显微镜及开尔文探针显微镜研究可调制的层间耦合作用下TMDs/石墨烯异质结构的电子结构及费米能级的变化规律。通过以上目标的实现，建立异质结构中层间耦合作用与激子态行为及电子结构的内在关联，为深入理解范德华异质结构的光学及光电性能奠定基础。

The exciton behavior of semiconductor heterostrucutures, including exciton generation, transfer, separation and recombination, is significant for understanding of fundamental physics and designing optoelectronic devices with high-efficiency. Compared with traditional semiconductor heterostructures, van der Waals heterostructures are ideal platforms for the study of exciton behavior, since there is no dangling bonds or lattice mismatch at the hetero-interface. The current proposal aims to tune the band alignment and interlayer coupling of TMDs/graphene heterostructures through the change of Femi level of graphene by means of electrochemical gating, and understand the relationship between interlayer coupling and exciton behavior (such as exciton types, binding energies and intensities), as well as charge transfer dynamics by virtue of photoluminescence spectra and transient absorption spectra. Scanning tunneling microscopy and Kelvin probe microscopy will be used to investigate the changes of electronic structures and Fermi levels of TMDs/graphene heterostructures under tunable interlayer coupling. The goals of present proposal are to establish the intrinsic correlation between interlayer coupling, exciton behavior and electronic structures of van der Waals heterostructures, and thus provide experimental understanding of their optical and optoelectronic properties.