Nitrogenated, phosphorated and arsenicated monolayer holey graphenes

Abstract

Motivated by a recent experiment that reported the synthesis of a new 2D material nitrogenated holey graphene (C₂N) [Mahmood et al., Nat. Commun., 2015, 6, 6486], the electronic, magnetic, and mechanical properties of nitrogenated (C₂N), phosphorated (C₂P) and arsenicated (C₂As) monolayer holey graphene structures are investigated using first-principles calculations. Our total energy calculations indicate that, similar to the C₂N monolayer, the formation of the other two holey structures are also energetically feasible. Calculated cohesive energies for each monolayer show a decreasing trend going from the C₂N to C₂As structure. Remarkably, all the holey monolayers considered are direct band gap semiconductors. Regarding the mechanical properties (in-plane stiffness and Poisson ratio), we find that C₂N has the highest in-plane stiffness and the largest Poisson ratio among the three monolayers. In addition, our calculations reveal that for the C₂N, C₂P and C₂As monolayers, creation of N and P defects changes the semiconducting behavior to a metallic ground state while the inclusion of double H impurities in all holey structures results in magnetic ground states. As an alternative to the experimentally synthesized C₂N, C₂P and C₂As are mechanically stable and flexible semiconductors which are important for potential applications in optoelectronics.