Epitaxial Growth of 2D Binary Phosphides

Combinations of phosphorus with main group III, IV, and V elements are theoretically predicted to generate 2D binary phosphides with extraordinary properties and promising applications. However, experimental synthesis is significantly lacking. Here, a general approach for preparing 2D binary phosphides is reported using single crystalline surfaces containing the constituent element of target 2D materials as the substrate. To validate this, SnP3 and BiP, representing typical 2D binary phosphides, are successfully synthesized on Cu2Sn and bismuthene, respectively. Scanning tunneling microscopy imaging reveals a hexagonal pattern of SnP3 on Cu2Sn, while alpha-BiP can be epitaxially grown on the alpha-bismuthene domain on Cu2Sb. First-principles calculations reveal that the formation of SnP3 on Cu2Sn is associated with strong interface bonding and significant charge transfer, while alpha-BiP interacts weakly with alpha-bismuthene so that its semiconducting property is preserved. The study demonstrates an attractive avenue for the atomic-scale growth of binary 2D materials via substrate phase engineering. The 2D binary phosphides, SnP3, and BiP, are fabricated by molecular beam epitaxy on Cu2Sn and bismuthene, respectively. Scanning tunneling microscopy/spectroscopy, complemented with theoretical calculations, reveals the evolution processes and physical properties. Interface interactions determine the phase and domain size of as-grown 2D phosphides, providing tailored properties with atomic-level precision.image