Strain-tunable band alignment of blue phosphorus–WX2 (X = S/Se/Te) vertical heterostructures: from first-principles study
In the scope of two-dimensional (2D) material study, blue phosphorus (BP) is a new graphene-like layered structure that has been successfully synthesized in the experiment after it was theoretically proved to be thermostable. These 2D structured functional materials have great potential in the next-generation nanoscale electronic devices for their unique features. Here, we composite BP and monolayer WX2 (X = S/Se/Te) based on van der Waals force (vdW) interaction to obtain well-defined type-II band alignment heterostructures. A systematic theoretic study was conducted to explore the interlayer coupling effects and the bands’ re-alignment of the BP–WX2 heterostructure after the strain was applied. Nowadays, many researches have proved that 2D materials can be used to degrade pollutants or used as a potential photovoltaic cell material to obtain high performance. We here twist BP and WX2 (X = S/Se/Te) into different angles to lay a theoretical framework on the band alignment and carriers’ separation. It reveals that the electronic properties of freestanding BP and WX2 can be roughly preserved in the corresponding heterostructures. Upon applying strain, band alignment exhibits significant adjustability through varying external strain. The heterostructures are type-II in a certain strain range, within which the carriers can be effectively separated spatially. These heterostructures undergo a transition from semiconductor to metal when a certain strain is imposed. This work not only provides a deep insight into the construction of heterostructures, but presents a new possibility for strain engineering that is both flexible and feasible and can be used for diverse applications.
KeywordsBlue phosphorus Heterojunction First principles
The authors acknowledge the financial support by the Science and Technology Research Program of Chongqing Municipal Education Commission (No. KJQN201800501, KJQN201900542, KJ1703042), the Program for Leading Talents in Science and Technology Innovation of Chongqing City (No. cstc2014kjcxljrc0023), the Natural Science Foundation of Chongqing (Grant No. cstc2019jcyj-msxmX0237), the National Natural Science Foundation of China (No. 11947105, 11904041), and Chongqing Normal University Fund Project (No. 17XLB012).
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Conflict of interest
There are no conflicts of interest to declare.