Atomically Thin p-n/p-n Nanodevices by Surface Charge Transfer Doping of Arsenene/Antimonene Heterostructures

Surface charge transfer doping (SCTD) is a promising technique to construct high-performance nanodevices because of its high reproducibility and high spatial selectivity and because it does little harm to the host semiconductor. Here, we performed a first-principles theoretical investigation to assess the effects of SCTD on the properties of two-dimensional (2D) arsenene, antimonene, and arsenene/antimonene van der Waals heterostructure as well. It was found that doping O or S on the surfaces of arsenene and antimonene could achieve efficient p-type doping, while doping Cs₂CO₃ on them could achieve n-type doping. Furthermore, when O and Cs₂CO₃ were co-doped on the two sides of the arsenene/antimonene heterostructure, a typical type-ii energy band alignment can be formed in O-arsenene/Cs₂CO₃-antimonene heterostructure, which effectively extends the range of the light absorption into the near-infrared region and facilitates the spatial separation of photogenerated electron-hole pairs. O- or S-doped arsenene and antimonene have tunable band gaps varying from 1.20 to 0.54 eV because of the doping-induced change of the conduction band minima (CBM), and Cs₂CO₃-doped arsenene and antimonene have band gaps of 2.02 and 1.36 eV, respectively, because of the changes of both valence band maxima and CBMs. This work offers a way to design p-n junctions with a tunable character, and the 2D p-n/p-n O-arsenene/Cs₂CO₃-antimonene heterostructure might be applied to electronic and optoelectronic nanodevices.