In-plane band bending in hexagonal monolayer WS2 by edge polarization

Abstract

A triangular domain structure within hexagonal monolayer WS2 is found to be induced by edge polarization. Based on density-functional theory calculations, the local electrostatic potential over WS2 is investigated, and with the S-adatom and S-2-addimer reconstructions at the W edges, the domains facing the W edges are found to be lower by up to 1.8 eV in the electrostatic potential than those facing the S edges. The edge-induced band bending in the terminated two-dimensional system is a two-dimensional analogy of the surface band bending effect in the terminated three-dimensional system. The largest potential difference is found to be comparable to the electronic gap of WS2, and near the edges, the W and S domains can be n- and p-type doped, respectively, by which the hexagonal monolayer WS2 can be applied to a bipolar electronic junction device.