Engineering Defect Transition-Levels through van der Waals Heterostructure

Tuning the defect transition levels in 2D semiconductors without significantly altering the integrity of the materials remains one of the most difficult challenges. Among the 2D materials, monolayer MoS₂ is considered as a front-runner for device applications, does not have a single intrinsic shallow defect, thereby limiting its applications. We demonstrate that the deep defect levels created by a cation vacancy in a monolayer of MoS₂, can be tuned to a shallow level by forming the van-der-Waals heterostructure of it with a monolayer of WS₂, while maintaining their structural and compositional integrity intact. In result, the deep defect levels are shallowed by nearly 4(V^-1_Mo) and 2(V^-1_W) times, respectively, compared to their monolayer counterparts. The overall change in dielectric constant rescales the defect transition levels in a heterostructure. Our finding has the potential to revolutionize the doping strategy of the 2D materials and could pave the way for 2D electronics.

Akash Singh, Aaditya Manjanath, and Abhishek K. Singh, Materials Research Centre, Indian Institute of Science, Bangalore 560012, India, Engineering Defect Transition-Levels through the van der Waals Heterostructure, J. Phys. Chem. C, Article ASAP, DOI: 10.1021/acs.jpcc.8b08082