Graphene-Sandwiched Van der Waals Heterostructures for Photodetectors

Next generation photodetectors are often considered to be constructed by two-dimensional (2D) materials. Preparing Van der Waals (vdW) heterostructures with stacked 2D material layers are becoming a novel method for the creation of new type of photodetectors. In this work, we designed and studied trilayer vdW heterostructures black-phosphorus (BP)/graphene/MoS
2
and blue-phosphorus (BlueP)/graphene/MoS
2
, in which graphene is sandwiched in between two different type of 2D materials. Using the first-principles calculation, the structural, electronic, and optical characteristic of the above heterostructures were investigated in detail. It is found that these two trilayer heterostructures are dynamically stable, suggesting that they can be practically prepared. Most monolayers in these heterostructures maintain their own good characteristics, which is beneficial to optimize the responsivity of 2D photodetectors. BP/graphene/MoS
2
opens the graphene bandgap effectively to be ~ 0.051 eV, appearing much larger than usual heterostructures and associated probably with build-in electric fields, and suggesting more application prospects in photodetectors. The semiconductor-characteristic quantum-well-like band alignment varies to match different application requirements. Together with the improved light absorption in the range of long-wave to short-wave infrared band, visible to ultraviolet band and solar-blind violet band, the proposed trilayer vdW heterostructures may serve as more prospective candidates for graphene-based 2D photodetectors.