First-principles calculations on strain and electric field induced band modulation and phase transition of bilayer WSe2[sbnd]MoS2 heterostructure.

A purposeful modulation of physical properties of material via change external conditions has long captured people's interest and can provide many opportunities to improve the specific performance of electronic devices. In this work, a comprehensive first-principles survey was performed to elucidate that the bandgap and electronic properties of WSe 2 MoS 2 heterostructure exhibited unusual response to exterior strain and electric field in comparison with pristine structures. It demonstrates that the WSe 2 MoS 2 is a typical type-II heterostructure, and thus the electron−hole pairs can be effectively spatially separated. The external effects can trigger the electronic phase transition from semiconducting to metallic state, which originates from the internal electric evolution induced energy-level shift. Interestingly, the applied strain shows no direction-depended character for the modulation of bandgap of WSe 2 MoS 2 heterostructure, while it exists in the electric field tuning processes and strongly depends on the direction of the electric field. Our findings elucidate the tunable electronic property of bilayer WSe 2 MoS 2 heterostructure, and would provide a valuable reference to design the electronic nanodevices. [ABSTRACT FROM AUTHOR]