Substrate induced anomalous electrostatic and photoluminescence propeties of monolayer MoS2 edges

Monolayer MoS2 is an emerging two-dimensional semiconductor with wide-ranging potential applications in the next generation electronic and optoelectronic devices. Understanding the influences of the supporting substrates on the physical properties of grown MoS2 is an important step toward its applications. Here we synthesized two typical rhomboid shaped MoS2 on MoO2 and triangle shaped MoS2 on SiO2/Si substrates and characterized them by multiple means of X-Ray Photoemission Spectroscopy, Atomic Force Microscopy, Electrostatic Force Microscopy, Raman and Photoluminescence techniques. We found that triangle shaped MoS2 exhibits different core level spectra compared with rhomboid shaped MoS2, attributed to dissimilar charge transfer with the underlying SiO2 substrate. Interestingly, the triangle shaped MoS2 single crystals exhibit distinct electrostatic and photoluminescence properties at center and edges. The underlying mechanism is proposed that partial decoupling of MoS2 at edges from SiO2 substrate induces different doping level and strain effects, resulting in anomalous physical properties at edges. The results reported here demonstrate that doping and strain effects induced by substrates have a significant influence on physical properties of monolayer triangle shaped MoS2，which can be generally applicable to other transition metal dichalcogenides materials.