Doping behaviors of adatoms adsorbed on phosphorene

Density functional theory calculations were performed to assess the electronic structures of single-layer phosphorene upon adsorption of various adatoms. Structural relaxations showed that adatoms belonging to a particular group exhibit similar behavior. The favorable configuration for adsorption of the adatoms is mainly determined by the unsaturated lone pairs on the phosphorene surface and the valence electron configuration of the adatoms. The unsaturated lone pairs enhanced the binding energies of the adatoms, indicating that phosphorene exhibits better adsorption capability for foreign atoms than graphene. Band structure calculations demonstrated that Li and Ag adatoms act as n-type dopants with low ionization energies. Pd adatom introduced p-type impurity states, thus acting as p-type dopants for phosphorene. Furthermore, the calculated energy barriers demonstrate that adatoms diffusion on phosphorene monolayer is quite anisotropic because of the puckered structure of the pristine phosphorene. Extra biaxial strain will not significantly influence the adsorption stability of adatoms and it seems impossible for us to release these adatoms by applying strain. This approach therefore offers a potential route for tailoring the electronic properties of phosphorene via adatom functionalization and should prove helpful for evaluating the performance of phosphorene-based electronic devices. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim