Tunable electronic properties and carrier mobility in binary pnictogen nanosheets, PX (X = As, Sb, and Bi)

Abstract

Electronic structures and electronic transport properties of binary pnictogen nanosheets, PX, (X = As, Sb, and Bi) are studied by the density functional method and are compared with those of the mono-elemental counterpart, blue phosphorene (PP). We find that both PAs and PSb, similar to PP, are indirect band gap semiconductors. However, an interesting indirect-direct band gap transition is predicted in PX when X = Bi, which originates from the upshifted energy level of valence p electrons and the enlarged vertical distance between atomic layers of P and X as the increasing atomic number of X atoms. Moreover, the transport properties in PBi nanosheets are also significantly improved, e.g., the hole mobility along the armchair direction in PBi is almost doubled as compared with that in PP. The direct band gap and enhanced carrier mobility in PBi suggest it holds greater promise for nanoelectronic and optoelectronic devices than the mono-elemental counterpart, PP.