Abstract
The discovery of the two-dimensional (2D) layered semiconductors, as transition metal dichalcogenide (TMDC), have gained interests due to their remarkable electronic and optical properties. The TMDC heterostructures offer a new platform for exploring new physics as well as future device applications. Therefore, the study of electronic structures of the TMDC heterostructures is crucial for potential usage in practical devices. In this study, we have performed the scanning photoelectron microscopy /spectroscopy measurements to investigate the electronic structure of vertical stacked WS2/MoS2 and MoS2/WS2 heterojunctions on the Si substrate and Au film surface. We investigated the interlayer coupling effect in TMDC heterostructures via photoluminescence and Raman spectroscopy. In addition, We have determined the band alignments of two vertical stacking TMDC heterostructures- WS2/MoS2 and MoS2/WS2 by van der Waals attraction. Moreover, the spontaneous polarization model in TMDC heterostructures was established by X-ray photoelectron spectroscopy. These results and findings open up venues to creating new material systems with rich functionalities and novel physics.