Engineering Defect Transition-Levels through the van der Waals Heterostructure

Tuning defect levels in 2D semiconductors without significantly altering the integrity of the materials remains one of the most difficult challenges, which critically restricts their usage in electronic and optoelectronic devices. In this study, we demonstrate that the deep levels created by a cation vacancy in a monolayer of MoS2 can be tuned to a shallow level by heterostructuring it with a monolayer of WS2, while maintaining their structural and compositional integrity intact. The overall change in dielectric constant rescales the defect transition levels in a heterostructure. As a result, the deep defect levels are shallowed by nearly 4 (VTMo-1) and 2 (V-w(-1)) times, respectively, compared to their monolayer counterparts. Our finding has the potential to revolutionize the doping strategy of the 2D materials and could pave the way for 2D electronics.