First principles study of impurity-doped black

Abstract

Recently, a newly fabricated two-dimensional layered material so-called phosphorene is receiving great research interests due to its peculiar physical properties. The phosphorene is a striking candidate for the next generation electronics due to its direct band gap and high carrier mobility. We report a density functional theory (DFT) study on the effects of substitutional doping of semiconducting elements on the electronic and magnetic properties of phosphorene. Here, we also explored the effect of the Fermi level shifting induced by an external charge carrier (hole and electron) doping. The doping of Ga, Ge, As and Se semiconductor elements is considered. The Ga impurity behaved as an n-type dopant, and a deep donor level was observed. In Ge doped system, we observed a metallic state while the band structure of As doped layer was very close to that of the pristine phosphorene. On the other hand, the magnetic state appeared in the Se doped phosphorene. With external electron carrier doping, the deep donor level induced by Ga impurity changed to shallow donor level with a magnetic moment of 1 µB in Ga atom. Due to the Fermi level shifting with extra charge doping, from metallic to semiconductor or vice versa was manipulated in Ge and As. For external hole carrier doping, all the system showed metallic band structures, except for the Se doped structure. In addition, we found no magnetic state in these four systems. Overall, we propose that the Ga doping can induce an n-type phosphorene and also the spin polarized state is observed. This may suggest that the Ga doping phosphorene has potential applications for both dilute magnetic semiconductor and p-n junction device applications.