... mechanically exfoliated. We find phosphorene to be stable and, unlike graphene, to have an inherent,direct, and appreciable band gap. Our ab initio calculations indicatethat the band gap is direct, ... counterpart of layered blackphosphorus, which we call phosphorene, as an unexplored p-typesemiconducting material. Same as graphene and MoS2, single-layer phosphorene is flexible and can be mechanically ... University, West Lafayette, Indiana 47907, United States,§Physics andAstronomy Department, Michigan State University, East Lansing, Michigan 48824, United States, and^School of Mechanical Engineering,...