Prediction of Green Phosphorus with Tunable Direct Band Gap and High Mobility.

Black phosphorus is an emerging material in nanoelectronics and nanophotonics due to its high carrier mobility and anisotropic in-plane properties. In addition, the polymorphism of phosphorus leads to numerous searches for new allotropes that are more attractive than black phosphorus in a variety of applications. On the basis of ab initio evolutionary crystal structure search computation, we report the prediction of a phosphorus allotrope called green phosphorus (λ-P), which exhibits direct band gaps ranging from 0.7 to 2.4 eV and strong anisotropy in optical and transport properties. Free-energy calculations show that a single-layer form, termed green phosphorene, is energetically more stable than blue phosphorene, and a phase transition from black to green phosphorene can occur at temperatures above 87 K. We suggest that green phosphorene can be synthesized on corrugated metal surfaces rather than clean surfaces due to its buckled structure, providing guidance to achieving epitaxial growth.