Semiconductor to Metal Transition, Dynamical Stability and Superconductivity of Strained Phosphorene

Very recently, field-effect transistors based on few-layer phosphorene crystals with thickness down to a few nanometres have been successfully fabricated, triggering interest in this new functional two-dimensional material. In this work, we apply the first-principles calculations to studying the evolution of electronic structures and lattice dynamics with vertical strain for monolayer and bilayer phosphorenes. It is found that, by changing the thickness of phosphorene or the strain applied on it, its band gap width can be well tuned, and there will appear a transition from semiconductor to metal. In particular, the bilayer phosphorene may become a good BCS superconductor by adjusting the interlayer distance, in which the interlayer van der Waals coupling is favorable to the dynamical stability against strain.