Lateral heterostructures of monolayer group-IV monochalcogenides: band alignment and electronic properties

Lateral semiconductor/semiconductor heterostructures made up of two-dimensional (2D) monolayer or few-layer materials provide new opportunities for 2D devices. Herein, we propose four lateral heterostructures constructed by phosphorene-like monolayer group-IV monochalcogenides, including GeS/GeSe, SnS/GeSe, SnSe/GeS and GeS/SnS. Using first-principles calculations, we investigated the energetics and electronic properties of these lateral heterostructures. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and can be easily synthesized in the laboratory. The band offsets of monolayer, bilayer and trilayer heterojunctions at the Anderson limit are calculated from the valence/conduction band edges with respect to the vacuum energy level for each individual component. Among them, some heterostructures belong to type II band alignment and are promising for a high-efficiency solar cell.